Square Feet Calculator
Calculate square footage instantly for rooms, flooring, paint, tile, carpet, landscaping, and renovation projects. Enter the length and width of your space, choose the unit you want to use, and see the total area in square feet, square yards, and square meters.
Enter your dimensions
Add the length and width of a rectangular space. You can measure in feet, inches, yards, or meters. The calculator converts everything automatically and shows the total square footage along with other common area units.
Area = length × width
Square feet conversion:
Inches → divide by 12 before multiplying
Yards → multiply by 3 before multiplying
Meters → multiply by 3.28084 before multiplying
Material estimate with extra waste = square feet × (1 + waste % ÷ 100)
Free Square Feet Calculator – Instantly Calculate Area for Any Room, Yard, or Surface
Working out square footage is one of those quiet, everyday skills that pays for itself over and over. It is the number the flooring store asks for before they will quote you. It is what tells you whether two gallons of paint will finish the bedroom or leave you staring at a half-covered wall. It is how you know whether the sofa you fell in love with will actually fit, how much mulch to haul home, and whether the house you are about to bid on is really the bargain the price-per-square-foot makes it look like. Learn to measure and multiply with confidence, and you stop guessing, stop over-ordering, and stop paying someone else to do arithmetic you can do yourself in under a minute.
At its heart, square footage is just a count of one-foot squares. Picture a floor tiled with squares that each measure a foot on every side; the number of tiles it takes to cover the surface is its area in square feet. For a plain rectangular room that idea could not be simpler, measure two sides, multiply, done. The trouble starts when a space refuses to behave: an L-shaped great room, a triangular corner bed, a round patio, a hallway that jogs around a staircase. That is exactly where most people either fudge a number or give up and phone a contractor. This page is here so you never have to. The calculator above does the math, and everything below explains the reasoning behind it, the formulas, the measuring tricks the pros actually use, and the real projects where getting the number right saves real money. If you are brand new to the whole idea, our companion guide on what square feet actually means is a friendly place to start.
Everything that follows is written to be read the way a knowledgeable friend would explain it: the fundamentals, how to handle every shape you are likely to meet, step-by-step use of the tool, a batch of fully worked examples pulled from ordinary home projects, the measuring mistakes that quietly cost people hundreds of dollars, and a long, plain-English FAQ. Alongside the calculator we keep a growing library of focused guides, on calculating square feet, measuring a room, and dozens of specific questions, and if your project spills outdoors into landscaping or bulk materials, the full home calculators section at WalDev has a tool for nearly every stage.
What square footage is, and why it keeps coming up
Square footage is the standard way area is measured in the United States for property, remodeling, and construction. One square foot is the space inside a square that is twelve inches on each side, roughly the size of a single floor tile, or a little larger than a sheet of printer paper. When a listing says a room is 200 square feet, it means 200 of those little squares would cover the floor with nothing left over and no overlaps. It is a measure of surface, flat and two-dimensional, which is what separates it from length (how far across something is) and from volume (how much space it holds). If the distinction between the flat number and the space it wraps around ever gets fuzzy, our explainer on what square feet is walks through it slowly with pictures in words.
The reason this number turns up everywhere is that so many decisions hang off it. Real-estate agents lean on price per square foot as the quickest apples-to-apples way to compare two homes on the same street. Contractors bid tile, carpet, siding, and roofing off it. Homeowners use it to buy the right amount of material the first time, sparing themselves the special trip back to the store for one more box. And it does not stop at materials: HVAC systems are sized to the conditioned area of a home, many building departments set permit fees or review thresholds by added square footage, and even something as ordinary as figuring out whether a bedroom set will fit starts with knowing the room is, say, 180 square feet. If you have ever wondered what a given number actually feels like to stand in, our guide on how big 1,000 square feet really is turns the abstraction into rooms and furniture you can picture.
A bit of perspective helps, too. According to the U.S. Census Bureau’s Characteristics of New Housing, the median new single-family home completed in 2025 was 2,142 square feet, and the median one sold was 2,194 square feet. Those are 2025 figures published by the Census Bureau in 2026, and they are smaller than a decade ago: new homes grew through the 2000s, peaked in the mid 2010s and have been shrinking since. For fun benchmarks at the extremes, people love comparing spaces to landmarks: a regulation football field is about 57,600 square feet, and the White House holds roughly 55,000 square feet of floor space across its six levels. Those comparisons are not just trivia; they train your eye to sanity-check a number, so that when a calculation spits out something wildly off, you notice.
One more thing worth settling early is how square feet relate to the other units you will bump into. Here is the short version, with a full guide behind each if you want to go deeper.
Square feet vs. square yards
One square yard is nine square feet, because a yard is three feet and 3 × 3 = 9. Carpet is still priced by the square yard in plenty of markets, so a wrong conversion here means a wrong order. Divide square feet by nine to land on square yards, the full walk-through lives in our square yard guide.
Square feet vs. square meters
One square meter is about 10.764 square feet. Anywhere the metric system rules, overseas listings, imported flooring specs, you will need this. Our square meter conversion guide covers both directions and the rounding that trips people up.
Square feet vs. acres
One acre is exactly 43,560 square feet, the standard unit for lots and land. That a 10,000-square-foot lot is only about 0.23 acres surprises a lot of buyers. We break down the number, the history, and the mental math in our guides on square feet in an acre and the reverse, acres from 10,000 square feet.
Square feet vs. cubic feet
Square footage is flat; cubic footage is the space above it. Multiply a room’s floor area by its ceiling height and you have its volume in cubic feet, a 150-square-foot room with 8-foot ceilings holds 1,200 cubic feet, the figure behind HVAC and air-quality math. The distinction, which snags nearly everyone at least once, is untangled in our square feet vs. cubic feet guide.
There are a couple of smaller conversions worth a bookmark, too. Down at the fine end, converting square inches to square feet comes up whenever you are working from tiny measurements (there are 144 square inches in a square foot). At the giant end, a square mile is 27,878,400 square feet, which is the scale news stories reach for when they describe wildfires or new developments. And if the phrasing “feet” versus “square feet” has ever tangled you up in a store, our short piece on feet versus square feet clears it up for good.
The area formula for every shape you will actually meet
Real rooms and yards do not come in one tidy shape, so it helps to keep a handful of formulas in your back pocket. The good news is that once you can name the shape, the formula is obvious, and anything that is not a clean shape can be chopped into pieces that are. Here is the full toolkit, from the rectangle you will use ninety percent of the time to the oddities you will meet once in a while.
Rectangle and square
By far the most common. Length times width, and you are done. Most bedrooms, living rooms, garages, and patios are rectangles, which is why the very first thing to learn is simply how to calculate square feet for a straight-sided space, everything else builds on it.
Area = Length × Width
Example: 15 ft × 12 ft = 180 sq ft
Triangle
Triangles show up in attic floors, corner garden beds, angled additions, and gable walls. The catch is that the “height” has to be the straight, perpendicular distance from the base to the far point, not the length of a slanted side. Get that right and the rest is easy.
Area = (Base × Height) ÷ 2
Example: (10 ft × 8 ft) ÷ 2 = 40 sq ft
Circle
Round patios, ponds, above-ground pools, decorative floor medallions. Measure straight across the widest point to get the diameter, halve it for the radius, then square the radius and multiply by pi. The classic slip is plugging in the diameter where the radius belongs, which quadruples your answer, our guide on finding the square feet of a circle shows how to avoid it and works through the triangle case too.
Area = π × radius² (π ≈ 3.14159)
Example: radius = 6 ft → 3.14159 × 36 = 113.1 sq ft
Trapezoid
You will meet a trapezoid in a room with one angled wall, or a lot with two parallel property lines of different lengths. You need both parallel sides and the perpendicular distance between them.
Area = ((Base 1 + Base 2) ÷ 2) × Height
Example: ((12 + 8) ÷ 2) × 10 ft = 100 sq ft
Ellipse
The stretched-oval shape turns up in ornamental beds, some pool designs, and fancy floor inlays. You need half the long diameter and half the short one.
Area = π × a × b (a = semi-major axis, b = semi-minor axis)
Example: π × 7 ft × 4 ft = 87.96 sq ft
L-shapes and other composite areas
Here is the one move that unlocks everything awkward: split the space into simple shapes, work out each one, and add (or subtract) the pieces. An L-shaped room is two rectangles. A room with a curved bay is a rectangle plus a half-circle. A yard with a corner clipped off is the big rectangle minus the missing triangle. That is the whole trick, and it scales to any floor plan no matter how strange.
Total Area = Area of Shape 1 + Area of Shape 2 + … (add sections)
, or,
Total Area = Area of Enclosing Rectangle − Area of Removed Sections
One habit worth keeping: before you calculate anything on an irregular space, sketch it and write every dimension right on the drawing. It takes thirty seconds and it stops you from mixing up which measurement belongs to which piece, the single most common source of a wrong total in a room with angles or cutouts.
Using the square feet calculator, step by step
The calculator at the top of this page handles the shapes you will actually use, rectangles, triangles, circles, and composites, so you do not have to remember a formula or do the arithmetic by hand. Getting a clean, trustworthy result takes about a minute if you go in with a plan rather than just poking at numbers.
Look at the space before you touch a tape measure and decide what it is. A plain rectangle? An L? A room with a bay window? Naming the shape, or the two or three shapes it breaks into, tells you exactly which measurements you actually need, so you are not stretching a tape across dimensions that do not matter.
A 25-foot tape covers most interior rooms. For a big yard, a 100-foot tape or a laser distance measurer saves your knees and gives cleaner numbers, a laser is especially handy in an empty room, where you point, click, and read. Measure at floor level, wall to wall along the baseboard, for the truest dimension.
Take each dimension the shape calls for and, if your tape reads feet and inches, turn the inches into a decimal by dividing by 12 before you do anything else. Thirteen feet six inches becomes 13.5 feet. Trying to multiply feet-and-inches in your head is the number-one way people end up off by a chunk, our guide on measuring a room shows the conversion in context.
Choose the shape that fits your space. For an L or a composite, run each rectangle separately, jot the results, and add them at the end. Honestly, most home jobs never need anything fancier than the rectangle option run once or twice.
Type in your measurements, double-check that everything is in feet rather than inches or meters, and calculate. For composite spaces, sum the section results for the true total.
For anything that gets cut, flooring, tile, wallpaper, shingles, pad your calculated area before ordering. Ten percent for a straightforward rectangular room with straight cuts; fifteen to twenty for diagonals, busy patterns, or lots of angles. That cushion is what keeps you from running out three rows short with a discontinued dye lot on the shelf. Our guide on figuring square feet for flooring walks through the whole waste-factor decision.
How to measure a room without fooling yourself
Measuring looks foolproof until a small habit throws you off by a couple of feet, enough to leave you short a box of tile or a gallon of paint. The routine below is essentially what a good flooring installer does, and it gets the number right on the first pass. If you want the fuller treatment, our dedicated guides on working out the square feet of a room and figuring the square feet of a whole house go room by room.
The plain rectangular room
Stand in the doorway and pick out the longest wall (the length) and the wall at a right angle to it (the width). Run the tape along the baseboard corner to corner on the long wall, read it in feet and decimal inches, then do the same on the short wall and multiply. As a check, measure each wall in two spots, low near the floor and higher up, because a real gap between the two readings means the walls bow or the room is out of square, which is worth noting before you order. A common room size to keep as a mental yardstick is the 12×12 room, which is 144 square feet; once you know what that feels like, you can eyeball most bedrooms within a few feet.
Whether to count closets and alcoves
It depends entirely on why you are measuring. For flooring and paint, include every surface you plan to cover, the closet floor needs flooring and its walls need paint just like the main room, and skipping them is a reliable way to come up short. For a real-estate listing, closets normally count toward the room; unfinished, unconditioned spaces normally do not. For heating and cooling, count every conditioned space, including the little closet that catches airflow from the room.
Built-ins, cabinets, and fixtures
Kitchen cabinets, a fixed vanity, built-in shelving, these sit on floor area but usually are not subtracted for a material estimate. Even though no flooring goes under a bolted-down vanity, it is simpler and safer to measure the full room and accept a sliver of extra material than to make finicky subtractions that could leave you short if a measurement drifts a little.
A measuring tip installers swear by: measure to the wall itself, never to furniture or an appliance. Tiling a kitchen? Pull the fridge and stove out and measure the full floor depth from wall face to wall face, not just the open floor you can see with everything in place. The gap behind the appliances still needs tile.
Taming irregular and complex spaces
Almost no real home is all perfect rectangles. Bay windows push out in curves and angles, open plans string two or three shapes together, garages sprout a bump-out, and yards wander along curved beds and crooked fence lines. The way through is always the same: break the mess into pieces you can measure, handle each one, and combine them.
Splitting an L-shaped room
The L is the irregular shape you will meet most. Draw an imaginary line off the inside corner, either direction works, the total comes out the same, and you are left with two rectangles. Measure each, calculate each, add them.
Worked Example – L-Shaped Open Plan
An open living-and-dining area makes an L. The long wing is 20 ft × 14 ft; the short wing runs 10 ft × 12 ft off the end. Split at the inner corner: 20 × 14 = 280 sq ft, and 10 × 12 = 120 sq ft. Total = 280 + 120 = 400 square feet.
The subtraction move
Sometimes it is easier to measure the whole bounding rectangle and take away the part that is missing. This is perfect for a U-shaped room or a rectangle with a chunk bitten out of one corner. Measure the full outer extent both ways for the bounding box, then measure the cutout and subtract it.
Worked Example – Room with a Staircase Cutout
The room’s full outer extent is 18 ft × 16 ft = 288 sq ft. A staircase eats a 6 ft × 5 ft corner that will not be floored. Cutout = 6 × 5 = 30 sq ft. Net floor area = 288 − 30 = 258 square feet.
Curves and bay windows
A semicircular bay adds the area of half a circle. Measure the straight edge where the bay meets the room (that is the diameter), halve it for the radius, and work out (π × r²) ÷ 2. Add it to the main room. Any half-round or quarter-round feature follows the same logic, and our circle area guide has more worked cases.
Wild outdoor outlines
For a backyard or bed with an organic, un-geometric edge, the graph-paper trick beats fussy geometry every time. Sketch the outline to a fixed scale, say one square equals one square foot, then count the whole squares inside the line and estimate the partial squares along the edge. It is plenty accurate for landscaping material and it works when the shape defies any clean description.
Square footage worked all the way through
Formulas click into place once you see them do real work. Here are the situations homeowners, contractors, and buyers run into most, each carried from raw measurement to the number you would actually act on.
Example 1 – Master bedroom plus walk-in closet
Scenario
A bedroom is 16 ft × 14 ft. Its walk-in closet is 8 ft × 6 ft. The owner is re-carpeting both.
Bedroom: 16 × 14 = 224 sq ft
Closet: 8 × 6 = 48 sq ft
Total: 224 + 48 = 272 sq ft
With a 10% waste factor: 272 × 1.10 = 299.2 sq ft, order at least 300 square feet of carpet.
Example 2 – Rectangular kitchen for tile
Scenario
A kitchen measures 22 ft 6 in × 11 ft 0 in, getting 12×12-inch porcelain tile.
Convert: 22 ft 6 in = 22.5 ft | 11 ft 0 in = 11 ft
Floor area: 22.5 × 11 = 247.5 sq ft
With 15% waste for tile cuts and breakage: 247.5 × 1.15 = 284.6 sq ft
Tiles: each 12×12 tile is exactly 1 sq ft, so buy at least 285 tiles, plus a few for future repairs.
Example 3 – Round paver patio
Scenario
A round brick patio, 18 feet across.
Radius: 18 ÷ 2 = 9 ft
Area: π × 9² = 3.14159 × 81 = 254.47 sq ft
With 10% waste for perimeter cuts: 254.47 × 1.10 = 279.9 sq ft
Order: about 280 square feet of pavers.
Example 4 – Triangular garden bed for mulch
Scenario
A corner bed has a 12-foot base along the fence and a 7-foot perpendicular depth to the tip.
Bed area: (12 × 7) ÷ 2 = 84 ÷ 2 = 42 square feet
For mulch at 3 inches deep: 42 sq ft × 0.25 ft = 10.5 cubic feet, ÷ 27 = 0.39 cubic yards. Since mulch sells by the cubic yard, order half a cubic yard to allow for settling, the mulch calculator does this step for you.
Example 5 – A whole home for a listing
Scenario
A single-story home with four rooms and a hallway, being prepped for sale.
Living room 18 × 15 = 270 | Kitchen/dining 20 × 14 = 280 | Bedroom 1 14 × 12 = 168 | Bedroom 2 12 × 11 = 132 | Bath 9 × 7 = 63 | Hall 18 × 4 = 72
Total finished area: 270 + 280 + 168 + 132 + 63 + 72 = 985 square feet. Our guide on figuring a house’s square footage covers what to include and exclude when the number will be published.
Want more of these? The library holds focused walk-throughs for the exact sizes people search, from the everyday 12×12 room to bigger benchmarks like 1,000 square feet, a two-car garage, and even the acre-scale comparisons in our how many square feet is 2 acres guide.
Turning square footage into a flooring order
Flooring is where an accurate number pays off most directly. Order short and you stop the job dead, and because hardwood and many tile lines are made in batches, a second order can arrive a shade off from the first, a mismatch you cannot fix without ripping everything out. Order way over and you have wasted money, since plenty of stores will not take back opened boxes. Our full guide on figuring square feet for flooring covers the whole workflow; here is the heart of it.
Start by totaling every surface that gets the same flooring, rooms, hallways, closets. Then pad that net figure with a waste factor matched to the material and the layout:
| Flooring Type | Standard Waste Factor | Notes |
|---|---|---|
| Vinyl plank (straight lay) | 10% | Minimal cuts; snaps together easily |
| Hardwood (straight lay) | 10–12% | Add more for bowed or cupped boards in the lot |
| Hardwood (diagonal lay) | 15% | Diagonal cuts drive waste up |
| Ceramic or porcelain tile | 10–15% | Use 15% for many cuts or out-of-square walls |
| Natural stone tile | 15–20% | Higher breakage; piece-to-piece variation |
| Carpet | 10–15% | Sold in 12-foot rolls; seam placement matters |
| Laminate (straight lay) | 10% | Stagger joints 6+ inches; plan cuts |
| Patterned tile or inlay | 20–25% | Pattern matching multiplies waste |
Carpet plays by its own rules. It comes off a 12-foot-wide roll, so the installer has to plan seams to keep them out of sight, and in an oddly shaped room you can end up needing quite a bit more than the bare floor area suggests because of how pieces cut from a fixed width. On a big carpet job it is often worth the free in-home measure. It usually costs nothing and heads off real waste.
Once the floor is handled, the same square-footage number feeds the rest of the room. If you are refreshing the walls too, the interior painting cost calculator and paint cost calculator turn your measurements into paint and labor estimates. And if the project is a whole-floor redo, our guide on a house’s total square footage keeps the room-by-room tally straight.
Square footage for painting is a different number
Paint trips people up because it is not the floor you measure. It is the walls, and sometimes the ceiling. You take the room’s perimeter, multiply by the ceiling height, then knock off the doors and windows you are not going to paint. Our companion guide on how many square feet a gallon of paint covers pairs perfectly with the wall math below.
Wall Area = Perimeter × Ceiling Height
Perimeter = 2 × (Length + Width)
Subtract: Doors (~21 sq ft each) and Windows (~15 sq ft each)
Worked Example – Painting a 14×12 Bedroom
Room 14 ft × 12 ft | Ceiling 8 ft | One door, two windows
Perimeter: 2 × (14 + 12) = 52 linear feet
Gross wall area: 52 × 8 = 416 sq ft
Subtract: 1 door (21) + 2 windows (30) = 51 sq ft
Net paintable wall: 416 − 51 = 365 sq ft
At 400 sq ft per gallon (one coat): 365 ÷ 400 = 0.91 gallons, buy 1 gallon for the first coat, 2 gallons if you want two solid coats.
Ceiling paint is just the room’s floor area. Most paint stretches 300–400 square feet a gallon depending on how smooth and thirsty the surface is; a rough textured ceiling drinks paint, so budget 300 for texture and 400 for smooth. For cabinet work specifically, the kitchen cabinet painting cost calculator gives a truer breakdown than a flat square-footage estimate ever could.
Worth knowing: the coverage on the can assumes ideal conditions, smooth walls, even application. In the real world you often get 10–15% less because of roller texture, wall porosity, and covering an old color. Buy a touch more than the math says, especially when you are matching an existing shade and a perfect pigment match matters.
Square footage outdoors: mulch, sod, gravel, and concrete
Outdoor projects use the same area math but bigger, messier spaces and different material units. Mulch sells by the cubic yard, seed by the pound per thousand square feet, fertilizer by coverage per bag, sod by the pallet, concrete by the cubic yard. In every case the square footage of the area is the starting number that everything else hangs on.
Seeding and fertilizing a lawn
Bags list coverage in square feet or square feet per pound. Break the lawn into rectangles, leaving out beds, the driveway, and the house footprint, add the sections, then divide by the product’s coverage to see how many bags or pounds you need.
Mulch and topsoil
Depth is what turns area into volume here. Multiply the bed’s square footage by the depth in feet (2 inches = 0.167 ft; 3 inches = 0.25 ft) for cubic feet, then divide by 27 for cubic yards, which is how bulk material is sold. Bagged mulch usually covers 8–12 square feet at 2 inches. The mulch calculator and topsoil calculator do the conversion the moment you have the bed area.
Asphalt and concrete
Driveways and walkways come by the cubic yard (concrete) or the ton (asphalt), and both start from surface area plus pour depth. A 20 ft × 40 ft = 800 sq ft driveway at 4 inches works out to 800 × (4/12) = 266.7 cubic feet ÷ 27 ≈ 9.9 cubic yards of concrete. The asphalt calculator handles the tons once you give it the area and depth.
Sod
Sod comes by the pallet, each covering roughly 450–500 square feet depending on supplier and grass. Measure the lawn, subtract beds and hardscape, divide by pallet coverage, and add 5–10% for cuts around obstacles. Measure carefully, because sod is perishable and has to go down fast.
Fill dirt
Grading, raised beds, and drainage fixes need dirt by volume: area in square feet, times average depth, for cubic feet. The dirt calculator converts it and factors in the settling that changes how much you truly need.
Square footage conversion reference
Keep this table handy for the conversions that come up in home improvement, real estate, and yard work, metric product specs, overseas listings, or the jump from area to volume for bulk material. Each row has a full guide behind it in the library below if you want the reasoning, not just the multiplier.
| From | To | Multiply By | Example |
|---|---|---|---|
| Square feet | Square meters | 0.0929 | 500 sq ft × 0.0929 = 46.45 m² |
| Square meters | Square feet | 10.764 | 50 m² × 10.764 = 538.2 sq ft |
| Square feet | Square yards | 0.1111 | 300 sq ft × 0.1111 = 33.3 sq yd |
| Square yards | Square feet | 9.0 | 25 sq yd × 9 = 225 sq ft |
| Square feet | Acres | 0.000023 | 43,560 sq ft = 1 acre |
| Acres | Square feet | 43,560 | 0.5 acre = 21,780 sq ft |
| Square feet | Square inches | 144 | 1 sq ft = 144 sq in |
| Square inches | Square feet | 0.00694 | 216 sq in = 1.5 sq ft |
| Square feet × depth (ft) | Cubic feet | area × depth | 200 sq ft × 0.25 ft = 50 cu ft |
| Cubic feet | Cubic yards | 0.037 | 50 cu ft ÷ 27 = 1.85 cu yd |
When a job crosses from area into volume, concrete, mulch, gravel, always put the depth into feet before you multiply, never inches. That one slip is where most volume errors are born. For the individual conversions, our guides on square meters, square yards, square inches, acres, and cubic feet each go one layer deeper, and the cubic yard calculator automates the volume side.
The measurement mistakes that quietly cost money
The expensive errors almost never come from hard math. They come from a short list of habits that are easy to fall into and just as easy to avoid once someone points them out.
Mixing feet and inches. Multiplying “14 feet 9 inches” straight against another dimension in decimal feet is the classic slip. Convert first: 14 ft 9 in = 14 + (9 ÷ 12) = 14.75 feet. Our guide on calculating square feet drills this until it is automatic.
Leaving closets and alcoves out of material estimates. If you are buying flooring or paint, every surface counts, closets, nooks, the short stub of hallway off the room. Measuring only the obvious main floor is a reliable path to coming up short.
Skipping the waste factor. No seasoned installer orders exactly the net area. Cuts, breakage, pattern matching, future repairs. They all want a buffer. Our flooring guide lays out the right percentage for each material.
Using interior dimensions for a listing. Standard U.S. real-estate square footage is generally measured to the exterior finished wall or the outer edge of the studs, not the inside trim line. Interior-only numbers read smaller than a formal appraisal, which creates awkward discrepancies in the listing.
Measuring at one spot in an old room. Homes built before the 1950s often have walls that are not quite parallel after decades of settling. One measurement is right at one point and wrong everywhere else, take two, near each end, and average them. Our room-measuring guide shows the two-point method.
Confusing linear feet with square feet. Baseboard, crown, and chair rail are bought in linear feet, the length around the room, not square feet. Adding up a perimeter and treating it as area produces a wildly wrong order. Our guide on square feet versus linear feet settles the difference for good.
Ignoring roof pitch on a roofing estimate. A house’s footprint is smaller than its sloped roof surface, a steep pitch can add 40% or more. Estimates that skip the pitch factor badly under-buy shingles. Pair the roof pitch calculator with our guide on square feet in a bundle of shingles to get the count right.
Using floor area to buy paint. Floor area and wall area are different numbers entirely. A 15 × 12 room with 9-foot ceilings has 180 square feet of floor but around 486 square feet of wall before doors and windows. Estimate paint off the floor and you will buy roughly a third of what you need, see how far a gallon really goes.
The complete Square Feet guide library
The calculator answers “how many square feet is this?” in a second. These guides answer the questions that come before and after that, how to measure, what a number means, what to buy, and how a space compares to something you already know. They are grouped by the kind of question they solve.
Understanding and measuring
Unit conversions
Picture the size
How much material to buy
Square footage questions people actually ask
These are the questions that come up again and again when people sit down to measure something. The answers are meant to be practical and specific, the kind you can act on right away.
How do I calculate square feet of a room?
Measure the length and width in feet and multiply them. A room 14 feet by 12 feet is 168 square feet. If the room is not a clean rectangle, split it into rectangles, do each one, and add the results. Always turn inches into decimal feet first, divide the inches by 12 and add them to the whole feet. Our full guide on the square feet of a room walks through the whole thing.
How many square feet is a 10×10 room?
Exactly 100 square feet, 10 feet times 10 feet. It is a handy mental benchmark, since plenty of smaller bedrooms and home offices land in the 80-to-120-square-foot range. For the next size up, see our guide on the 12×12 room, which is 144 square feet.
How do I convert inches to feet for area calculations?
Divide the inches by 12 before multiplying. A room 150 inches by 120 inches becomes 12.5 feet by 10 feet, or 125 square feet. When a tape reads feet and inches together, 13 feet 6 inches, convert only the inches (6 ÷ 12 = 0.5) and add them: 13.5 feet. The step-by-step is in our calculating square feet guide.
How do I calculate square footage for an L-shaped room?
Split the L into two rectangles with an imaginary line off the inside corner, either direction gives the same total. Measure and calculate each rectangle, then add them. If one part is 18 × 12 = 216 and the other is 10 × 9 = 90, the room is 306 square feet.
How do I calculate square feet for flooring?
Measure each room’s length and width, multiply, and add all the rooms together, closets included. Then add a waste factor: 10% for a straight lay, 15% for diagonals or lots of cuts. Round up to whole boxes when you order. The complete method, material by material, is in our flooring square footage guide.
How many square feet is an acre?
Exactly 43,560 square feet, a fixed, legal conversion. Divide square feet by 43,560 to get acres, so a 10,000-square-foot lot is about 0.23 acres, and a quarter-acre is 10,890 square feet. We cover it fully in square feet in an acre and the quarter-acre guide.
How do you figure out square footage of an odd-shaped area?
Break it into simple shapes, rectangles, triangles, half-circles, calculate each with its formula, and add them up. For a truly organic outline, sketch it on graph paper to scale and count the squares inside the line, estimating the partial ones at the edge. Our circle and odd-shape guide has the geometric cases worked out.
What is the formula for the area of a circle in square feet?
Area = π × r², where r is the radius (half the diameter). A patio 14 feet across has a 7-foot radius, so 3.14159 × 49 ≈ 153.9 square feet. The frequent mistake is using the diameter where the radius belongs, which makes the answer four times too big, our circle guide shows how to keep it straight.
How do I measure square footage for paint?
Multiply the room’s perimeter by the ceiling height for gross wall area, then subtract about 21 square feet per door and 15 per window. Most paint covers 350–400 square feet a gallon on smooth walls, so divide net wall area by that for one coat and double it for two. Full detail is in how far a gallon of paint goes.
How do I calculate how much mulch I need using square footage?
Find the bed’s square footage, pick a depth (2–3 inches is typical), and convert the depth to feet (2 in = 0.167 ft; 3 in = 0.25 ft). Multiply area by depth for cubic feet, then divide by 27 for cubic yards. So 300 sq ft at 3 inches is 300 × 0.25 = 75 cubic feet ÷ 27 ≈ 2.8 cubic yards, or let the mulch calculator do it.
What is the difference between square feet and linear feet?
Square feet measure area, a two-dimensional surface. Linear feet measure length only. Flooring, tile, and paint go by square feet; trim, baseboard, fencing, and pipe go by linear feet. Carpet is the tricky one: it is sold off a fixed-width roll but you plan it from square footage first. Our guide on square feet versus linear feet untangles it.
How many square feet is 12×24?
288 square feet (12 × 24). That is a common footprint for a one-car garage, a roomy studio, or a generous deck. At that size you would want about 2 gallons of floor paint, roughly 320 square feet of tile with a 10% waste factor, or about 32 square yards of carpet. For the two-car version, see square feet of a 2-car garage.
Should I include closets when calculating a room’s square footage?
It depends on the purpose. For flooring and paint, always include them, those surfaces get covered too, and leaving them out means running short. For a real-estate listing, closets normally count toward the room. For heating and cooling, include all conditioned closet space. The main exception is formal appraisal under specific measurement standards, which vary by market.
How do I convert square meters to square feet?
Multiply square meters by 10.764. A 75-square-meter apartment is 75 × 10.764 = 807.3 square feet. Going the other way, multiply square feet by 0.0929. It comes up constantly with overseas listings and European flooring specs, the full conversion, both directions, is in our square meter guide.
How do I calculate square footage for a roof?
Start with the house footprint, then multiply by the roof’s pitch factor for the slope, 1.0 for flat, about 1.118 for a 6/12, and 1.414 for a 12/12. Divide the adjusted area by 100 to get roofing “squares,” since materials sell that way. Pair the roof pitch calculator with our guide on square feet in a bundle of shingles for the full count.
Is real-estate square footage measured the same way everywhere?
Not exactly. In residential real estate, square footage means the finished, heated, livable area, but there is no single national standard, markets, listing services, and appraisers differ. Many appraisers follow the ANSI Z765 standard, which measures from exterior walls and counts only above-grade finished space; whether a finished basement counts varies by market. Always confirm which method applies to a given listing.
How much does square footage affect home value?
A lot, but the effect swings wildly by location. In dense cities, price per square foot can top several hundred dollars, so even 100 extra square feet on a listing is real money. In rural markets, land and location matter more than raw size. Appraisers use comparable sales to set a price-per-square-foot benchmark for a specific neighborhood, so local data, not national averages, drives any one home’s value.
How do I calculate the square footage of a staircase?
For flooring or carpet, take one tread’s width times its depth, multiply by the number of steps, and add the riser faces if you are covering them (riser height × tread width × steps). For a 14-step run with 36-inch-wide, 10-inch-deep treads, the tread area is (3 ft × 0.833 ft) × 14 ≈ 35 square feet, plus risers. The stair calculator helps with full stair planning.
