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01 · The map

Twelve sections, 1,143 articles, and one thing they all have in common

This is the writing side of a calculator site. Every section below grew up around a tool, because the questions people ask before and after they run a calculation turn out to be more interesting than the calculation. Someone works out a roof pitch and then wants to know whether the code will let them put shingles on it. Someone converts an hourly rate to a salary and then wants to know what actually lands in the account. The tool answers one question. The section answers the rest.

What every section has in common is the problem of the number. A calculator is only useful if the figure you type into it is real, and most of the figures people carry around are a year or two out of date, half remembered, or were never published by anybody in the first place. That problem shows up differently in tax than it does in roofing or in medicine or in a video game, and the sections below are organized around those differences.

Section	What it covers	Articles	The figures it depends on
Finance	VA loans, salary and take-home pay, living wage, land loans, interest rate caps, lottery tax	242	IRS, SSA and FHFA, reset every January
Health	Blood pressure, kidney function and creatinine, contraception	209	FDA labels and CDC guidance, by edition
Education	AP exams, scoring, difficulty and pass rates	149	College Board, updated each exam year
Pets	Cats and dogs: dosing, triage, normal vital signs, food safety	147	Veterinary references and poison control data
Home	Pools, topsoil, square footage, board feet	95	CDC pool guidance, ANSI measurement standards
Business	Tipping, service charges, what people actually pay	72	Survey data, which is not the same as a rule
Gaming	Diamond Dynasty PXP, Classic WoW talents, Pokemon	67	Patch notes, when the publisher writes any
Food	Chipotle, Cava and Starbucks nutrition and ordering	58	Company nutrition data, changed without notice
Lifestyle	Audiobooks: listening speed, subscriptions, cancellation	57	Consumer protection law and platform terms
Construction	Roof pitch, slope, rafters and materials	34	The IRC, but only where it has been adopted
Crafts and Hobbies	Cross stitch fabric counts and sizing	8	Fabric specifications, stable for decades
Automotive	Car paint coverage and estimating	5	Manufacturer coverage rates

Why a calculator site ends up writing this much

A tool answers a closed question. You give it a rate and a term and it gives you a payment. What it cannot do is tell you whether the rate you typed is the rate you will get, whether the payment it produced is the payment you will actually make, or whether the whole calculation was the right one to run. Those are the questions people arrive with, and they are the reason the articles exist.

They also explain why the sections look so unalike. A tax question is answered by finding the current published figure. A veterinary question is answered by weight and by how long ago it happened. A roofing question is answered by the code edition your county adopted. A question about a video game may have no published answer at all, only measurements that players took. The work of each section is mostly the work of finding out which kind of question it is.

Article counts are live category counts as of 18 August 2026 and include every child category. The four figures at the top of the site, Finance, Health, Education and Pets, account for roughly two thirds of everything written here.

02 · The framework

Six kinds of number, and how fast each one goes stale

People treat every figure they read as though it has the same shelf life. It does not. A number published by a federal agency, a number written into a building code, a number printed on a drug label, a number set by a game studio, a number decided by a restaurant chain and a number produced by a survey all change on completely different schedules, for completely different reasons, and they fail in completely different ways. Knowing which kind you are holding tells you how much to trust it and when to go and look again.

These six categories cover almost everything on this site.

Kind of number	Who sets it	How often it moves	How you find out it moved
Agency figures	IRS, SSA, FHFA, DOL	Annually	Announced in the autumn for the following year
Market rates	The market, surveyed by Freddie Mac, the Fed, the FDIC	Daily to monthly	Published on a fixed schedule, easy to check
Codes and standards	ICC, ANSI, then each state and city separately	Every 3 years	Only when your jurisdiction adopts the new edition
Clinical guidance	FDA labels, CDC criteria, specialty bodies	Irregular	Often not at all. Labels change quietly
Company data	The company	Whenever it likes	You do not. There is no notice and no archive
Survey data	Pew, BLS, industry researchers	Per study	A new study, which may not agree with the last one

Agency figures look permanent and are not

This is the most common failure on the internet, and it is the easiest to check. Tax brackets, the standard deduction, retirement contribution limits, the Social Security wage base and the conforming loan limit all reset on 1 January, and they are all announced months in advance in a document with a number on it. A page written in March that quotes the current standard deduction is correct in March and wrong the following January, and nothing about it changes to signal that. It just sits there, confident and stale.

The tell is the absence of a year. A page that says the standard deduction is a figure has told you nothing you can act on. A page that says it is that figure for tax year 2026, per Revenue Procedure 2025-32 has told you both the number and its expiry date, which is the useful part.

Market rates are perishable and honest about it

Mortgage rates, Treasury yields, the prime rate and deposit averages move constantly, and nobody pretends otherwise. The risk with these is not staleness so much as false precision: a survey average is not an offer, and the national average savings rate is the floor of the market rather than the middle of it. The FDIC put the national savings average at 0.38 percent in August 2026 while competitive accounts paid several times that. Both figures are true. They answer different questions.

Codes are not national, and that surprises almost everyone

The International Residential Code is published by a private non-profit and has no legal force anywhere until a state, county or city adopts it. Jurisdictions routinely sit an edition or two behind and add their own amendments on top. Two houses on opposite sides of a state line can be under genuinely different rules about what you may put on a roof. So a page that states a minimum roof slope as though it were federal law is wrong in a way that is invisible until an inspector tells you.

The same applies to measurement standards. Whether a square footage figure is comparable to another one depends on which standard was used to produce it, and the answer is frequently that nobody recorded which.

Clinical guidance changes without an announcement

Drug labels are revised, criteria are re-issued in new editions, and the old version stops being current without anything visible happening on the pages that quoted it. In December 2022 the FDA approved the deletion of a sentence from the Plan B label about preventing implantation, on the basis that the evidence did not support it. Enormous numbers of pages still describe the old mechanism, because deleting a sentence from a label does not send anyone an email.

The harder version of this problem is a figure that was never in the guidance at all but travels as though it were, which is common enough in health writing to deserve its own section below.

Company data has no archive and no obligation

Nutrition figures, menu prices, subscription terms and game mechanics are all set by a company that can change them on a Tuesday and is under no duty to tell anyone or to keep a record. Blizzard deleted its own 2006 patch notes, so the numbers an entire community relies on now survive only in fan archives. Restaurant nutrition data is revised whenever a supplier changes. A figure in this category should always be read as a snapshot with a date attached, never as a fact.

Survey data is the sixth kind, and the most misread

Some numbers are neither rules nor market prices. They are measurements of what people did, produced by a researcher who asked. Tipping is the clearest case on this site: nobody sets a tipping rate, no agency publishes one, and the figures that circulate are either survey findings or somebody's opinion dressed as etiquette. A survey finding that most people tip a certain amount at a restaurant is a real, useful, checkable fact about behavior. It is not an obligation, and it does not become one by being repeated.

Two things go wrong with survey data specifically. The first is that the population gets dropped: a figure drawn from one country, one income band or one kind of establishment gets quoted as though it described everyone. The second is that surveys disagree, and the one that gets repeated is usually the one with the roundest number rather than the largest sample. When a behavioral figure matters to you, the question is who was asked, how many of them, and when.

The same caution applies to any average presented as a norm. An average is a description with a distribution behind it, and the distribution is often the interesting part. Knowing the average size of a new house tells you much less than knowing that half of them are smaller than it.

The practical version. Before you rely on a number, decide which of the six it is. That tells you whether to recheck it this week, this January, when you pull a permit, or every single time. It also tells you where to look, because each category has one obvious publisher and a lot of unreliable copies.

03 · What changed

The 2026 figures that most pages still have wrong

Everything in this table changed for 2026 and was announced in advance. Every one of them is still being quoted at its old value across large parts of the internet, including on pages that look authoritative. These are the ones worth checking first if you are reading anything written about money, work or housing.

Figure	2025	2026	Published by
Form W-2G reporting threshold	$600	$2,000	IRS, and indexed to inflation from here on
Standard deduction, single	$15,750	$16,100	IRS Rev. Proc. 2025-32
Standard deduction, married filing jointly	$31,500	$32,200	IRS Rev. Proc. 2025-32
Top 37% bracket starts, single	$626,350	$640,600	IRS Rev. Proc. 2025-32
401(k) elective deferral	$23,500	$24,500	IRS Notice 2025-67
Age 50 catch-up	$7,500	$8,000	IRS Notice 2025-67
IRA contribution limit	$7,000	$7,500	IRS Notice 2025-67
Social Security wage base	$176,100	$184,500	Social Security Administration
Conforming loan limit, one unit	$806,500	$832,750	Federal Housing Finance Agency
Commuter and parking benefit, monthly	$315	$340	IRS Rev. Proc. 2025-32

The standard deduction did something stranger than move

The 2025 standard deduction was announced in late 2024 as $15,000 for a single filer and $30,000 for a couple filing jointly. Those were the correct figures, from the correct document, until the One Big Beautiful Bill amended the underlying statute in July 2025 and raised them retroactively for that same tax year to $15,750 and $31,500. The IRS restated them in Revenue Procedure 2025-32, which formally modified the earlier one.

So a page written in June 2025 quoted the right number from the right source and was wrong by August, without the year changing and without anything on the page looking different. That is the failure mode in its purest form, and it is the reason a figure is only as good as the document and date attached to it. The 2025 column above uses the final amended figures, not the ones originally announced.

Three that did not change, and get reported as though they had

The opposite error is just as common. These have not moved, and confident writing to the contrary is everywhere.

The federal minimum wage is still $7.25 an hour, where it has been since 24 July 2009. State minimums have moved a great deal. The federal floor has not moved in seventeen years.
The federal overtime salary threshold is back at $684 a week, which is $35,568 a year. A 2024 rule would have raised it substantially, but a federal court vacated that rule in November 2024, and the Department of Labor is applying the 2019 level. In May 2026 it issued a technical amendment striking the vacated rule from the regulations, which changed the paperwork and not the number. Meeting the salary level does not by itself make a role exempt: the duties test still has to be satisfied.
The 43 percent debt-to-income cap is gone. It was removed from the general qualified mortgage rule and replaced with a price-based test, effective for loans from October 2022. Lenders still look hard at debt-to-income, and there is no longer any federal rule that names that threshold. It is quoted constantly as though it were still law.

And one where the direction of travel is backwards

New houses are usually described as getting bigger. They have been getting smaller for a decade. The Census Bureau put the median new single-family home completed in 2025 at 2,142 square feet, and the median one sold at 2,194. Both are down from a peak in the middle of the 2010s. The received wisdom is a decade out of date, and the number that gets repeated is often 2,300 or higher.

Where the current rates sat when this was written. The federal funds target range has been 3.50 to 3.75 percent since December 2025 and every 2026 meeting so far has held it there. The bank prime rate was 6.75 percent on 14 August 2026, the 10-year Treasury 4.72 percent on 17 August, and Freddie Mac put the 30-year fixed mortgage average at 6.67 percent for the week of 13 August. Consumer prices were up 3.4 percent over the twelve months to July 2026. All five move on their own schedule, so treat them as dated readings rather than as facts.

04 · The unsourced ones

Widely repeated figures that no official body publishes at all

The stale number is the easy problem. The harder one is the figure that was never published by anybody, has no document behind it and no mechanism for ever being corrected, but is repeated so consistently that it reads exactly like guidance. These turn up in every section of this site, and the pattern is always the same: a plausible number, no attribution, and total confidence.

Here are the ones worth knowing about, with what the sources actually say.

Health

The claim that emergency contraception stops working above 165 or 195 pounds. No FDA-approved label sets a weight or BMI limit for either pill. The words weight and BMI do not appear in the Plan B label. The 165 figure is 75 kilograms converted, a threshold that appeared only on a European product label in November 2013 and that the European Medicines Agency deleted in July 2014, concluding the products can continue to be used at all weights. It was never adopted in the United States. What the CDC does say is narrower: emergency contraceptive pills might be less effective at a BMI of 30 or above than below 25, with no safety concern and no restriction on use.
The copper IUD being "99.9 percent effective." The World Health Organization publishes "more than 99 percent." The decimal comes from a systematic review of 42 studies that found a pregnancy rate of 0.09 percent. That is a real and impressive figure, and it belongs to the review, not to WHO or the CDC.

Money

The 28/36 rule. Housing costs under 28 percent of gross income, total debt under 36. It describes conventional underwriting convention. No consumer protection, housing or banking agency publishes it as guidance.
The 4 percent withdrawal rate. Independent research published in a financial planning journal in 1994, plus later work building on it. Useful analysis, not a federal standard, and no agency endorses it.
Buying a house worth three times your salary. No agency publishes a salary multiple for house prices. The ones that discuss affordability at all discuss payment-to-income ratios.
Land loans costing "1 to 3 percent more" than a mortgage. No federal agency publishes a spread between the two, and there is a structural reason: the federal mortgage pricing dataset explicitly excludes loans secured by unimproved land, and bank regulators collect land loan balances without collecting land loan rates. The one comparison that can be made from published data is far narrower than 1 to 3 points.

Games

Diamond Dynasty PXP thresholds, per-action values and multipliers. San Diego Studio publishes none of them. Not one threshold, value or multiplier appears in the manual, on the official site, in the support pages or in any patch note. The figures in circulation come from community measurement, and the largest community sources disagree with each other on several of them. That does not make them useless. It makes them measurements, which should be labeled as measurements.

Building

A national minimum roof slope. There is no such thing. The International Residential Code sets minimums by covering, each with a section number, but it is a model code with no force until a jurisdiction adopts it, and jurisdictions sit on different editions with local amendments.

How to spot one. A published figure comes with two things: a name and a date. A convention comes with neither, because there is nobody to attribute it to and nothing that would ever cause it to be revised. When a number has been repeated to you ten times and you still cannot name who published it, that is the answer.

None of this means the conventions are bad advice. The 28/36 ratios describe real lender behavior. The 4 percent figure came out of careful work. What creates the problem is the transfer of authority: a convention repeated often enough loses its origin, and a reader meeting it for the tenth time has no way to tell it apart from a published limit. People then rule out options that were available to them, or take comfort from a threshold that nobody stands behind.

05 · Reading a figure

Four questions that settle almost any number you find

This is the working method behind everything on this site, and it takes about a minute per figure. It is not skepticism for its own sake. Most numbers survive it comfortably, and the point is to find the ones that do not before you act on them.

Ask	A good answer looks like	A bad answer looks like
Who published it?	A named agency, company, journal or standards body	"Experts say", "it is generally accepted", nobody
When?	A year, a quarter, a survey week, an edition	No date anywhere on the page
Does it apply to me?	Your filing status, your state, your code edition	A national figure treated as your figure
Is it a rule or an average?	Stated plainly as one or the other	An average quoted as though it were a limit

The third question is the one people skip

Most bad outcomes do not come from a wrong number. They come from a right number that belonged to somebody else. A national mortgage average is a survey of what lenders offered, not a quote for your credit and your down payment. A national deposit average is a floor, not a target. A median new home size is not the size of the home you are looking at. A federal minimum wage is irrelevant in a state with a higher one. Each of those figures is correct and each of them is the wrong input for an individual decision.

The same applies to codes and to clinical criteria. A slope minimum is only your minimum if your jurisdiction adopted that edition. A drug label applies to the product as approved where you are, and a European label is not a United States label, which is precisely how the weight limit described above traveled so far.

The fourth question, which decides how hard you can lean

A rule is a boundary somebody will enforce. An average is a description of what happened. They look identical on a page and behave completely differently. Being told that the average tip is a certain percentage tells you what people did; it does not tell you what you owe. Being told a supervisory loan-to-value limit for raw land is 65 percent tells you what a bank examiner will look for, which is a real constraint even though it is written as guidance for the bank rather than as a cap on you.

When a page will not tell you which of the two it is showing you, that is itself information about how carefully the page was assembled.

The one habit worth forming. When a calculator asks you for a figure, go and get the real one before you type. On a mortgage that means the actual tax bill for the specific parcel and one real insurance quote, which takes twenty minutes and moves the answer more than shopping half a point off the rate. On a medication it means the current label. On a game it means the current patch. The tool cannot know what it was not told, and the difference between a remembered number and this week's number is usually larger than the difference between the tools you are choosing between.

Why every section here is written this way

Every article on this site is meant to name its sources and date its figures, and to say plainly when something is a convention rather than a rule. That is not a stylistic preference. It is the only way a page about a number stays useful after the week it was written, and it is the difference between a page you can check and a page you have to trust.

06 · Where to start

All twelve sections, and the twenty-four collections inside them

Each section below has its own hub page with the material specific to that subject. The collections underneath are where the articles actually live. Post counts are current as of 18 August 2026.

Finance

242 articles. The largest section, and the one where figures go stale fastest, because almost everything in it resets in January.

VA Loan66 articles on eligibility, the funding fee, assumption and refinancing.
Lottery37 on withholding, the lump sum decision and the real odds.
Salary37 on converting pay, and on what reaches the account.
Living Wage31 on what an income needs to be to cover local costs.
Interest Rate Cap30 on pricing caps for floating-rate borrowers.
Land Loan28 on financing raw land, which is underwritten differently.
Illinois Salary13 on Illinois-specific withholding and take-home pay.

Health

209 articles. Everything here is checked against the label or the published criteria, and says so.

Blood Pressure102 on readings, staging, and what the numbers mean.
Creatinine80 on kidney function, eGFR and what moves a result.
Contraception27 on emergency contraception, timing and effectiveness.

Education

149 articles, all on Advanced Placement, from choosing a subject to reading a score.

AP Exam149 on exam length, format, difficulty and score distributions.

Pets

147 articles. The section with the highest proportion of genuinely urgent questions.

Cat124 on health, behavior, vital signs and what to do at 2am.
Dogs23 on food safety, toxic doses and the ten percent rule.

Home

95 articles on measuring, estimating and buying the right quantity of things.

Pool35 on chemistry, sanitation and salt water systems.
Topsoil28 on volume, coverage and what the word actually means.
Square Feet24 on area, conversions and measurement standards.
Board Foot8 on lumber volume and pricing.

Business

72 articles, mostly on tipping, where the gap between the rule and the practice is the whole story.

Tips72 on tipping rates, service charges and what people actually do.

Gaming

67 articles. The section where the publisher often documents nothing and the community measures everything.

Wow Talent30 on Classic talent builds across several live versions.
PXP29 on Diamond Dynasty parallel progression and grinding.
Pokemon8 on type matchups and damage.

Food

58 articles on chain restaurant nutrition and ordering, where the data changes without notice.

Chipotle48 on building a bowl, calories and what things cost.
Cava5 on bowls, dressings and nutrition.
Starbucks5 on drinks, sizes and caffeine.

Lifestyle

57 articles on audiobooks, including the part most guides skip, which is the contract.

Audiobook57 on listening speed, credits, subscriptions and cancellation.

Construction

34 articles on roof geometry, and on the code that decides what you may put on it.

Roof Pitch34 on slope, angle, rafter length and minimum pitches by material.

Crafts and Hobbies

8 articles on cross stitch, where the arithmetic is simple and getting it wrong is expensive in fabric.

Cross Stitch8 on fabric count, finished size and how much to buy.

Automotive

5 articles on paint estimating, the smallest section here and the one with the clearest question.

Car Paint5 on coverage, quantity and what a respray needs.

The tools these sections were built around are in the calculators collection, and the homepage holds everything.

07 · Questions

Questions about using this site, answered with the source named

What is the standard deduction for 2026?

$16,100 for a single filer, $32,200 for a married couple filing jointly and $24,150 for a head of household, set out in IRS Revenue Procedure 2025-32. For tax year 2025 the final amounts were $15,750 and $31,500, raised retroactively during that year.

Is the W-2G gambling reporting threshold still $600?

No. For payments made in calendar year 2026 it is $2,000, and it is indexed to inflation from now on. The separate 24 percent withholding threshold is unchanged at proceeds over $5,000.

Why does a mortgage calculator understate my real payment?

Because it computes principal and interest only. Property tax, homeowners insurance, mortgage insurance and any association dues sit on top, and the first two are usually collected monthly into escrow. Both are public or one phone call away for a specific address.

Is there a national minimum roof pitch?

No. The International Residential Code sets minimums by covering, each with its own section number, but it is a model code published by a private non-profit and carries no force until a state, county or city adopts it. Jurisdictions sit on different editions and add local amendments.

Does emergency contraception stop working above a certain weight?

No FDA-approved label sets a weight or BMI limit. The figure in circulation traces to a European label from November 2013 that the European Medicines Agency deleted in July 2014, and it was never adopted in the United States. The CDC position is that the pills might be less effective at a BMI of 30 or above than below 25, with no safety concern and no restriction on use.

Where do the game figures come from if the publisher does not publish them?

Community measurement, and this site labels them as such. For Diamond Dynasty parallel progression in particular, San Diego Studio has never published a threshold, a per-action value or a multiplier, and the largest community sources disagree with each other on several values.

How current are the rates quoted across the site?

Each figure carries the date it applies to, because they move on different schedules. Mortgage rates are surveyed weekly, Treasury yields daily, deposit averages monthly, contribution limits and loan limits annually. A figure without a date is not something you can act on, here or anywhere.

What is the federal minimum wage in 2026?

$7.25 an hour, unchanged since 24 July 2009. Many states set a higher one, and where they do, the higher figure applies.

08 · Sources

Where the figures on this page come from

Everything numeric above is published by a federal agency, a standards body or a named study, and each carries the date it applies to. Rates move, so check the source before relying on a figure here.

2026 tax figures and the retroactive 2025 amendment. IRS Revenue Procedure 2025-32, and the IRS release on the 2026 inflation adjustments, which also restates the amended 2025 standard deduction.
Retirement contribution limits. IRS announcement of the 2026 limits and IRS Notice 2025-67.
The W-2G threshold. IRS Instructions for Forms W-2G and 5754, which carry both the 2026 reporting threshold and the 24 percent withholding rule.
Social Security wage base. SSA contribution and benefit base.
Conforming loan limits. FHFA, 2026 conforming loan limit values.
Overtime threshold. Department of Labor, earnings thresholds for the executive, administrative and professional exemption, and the DOL rulemaking FAQ on the vacated 2024 rule.
Federal minimum wage. Department of Labor, minimum wage.
Rates. Freddie Mac Primary Mortgage Market Survey for the week of 13 August 2026, Federal Reserve H.15 for the prime rate, the FOMC statement of 29 July 2026 for the target range, and the FDIC national rates and rate caps for August 2026 deposit averages.
Inflation. BLS Consumer Price Index, twelve months ending July 2026.
New home size. Census Bureau, Characteristics of New Housing, 2025 data.
The qualified mortgage rule. CFPB general qualified mortgage loan definition final rule, which replaced the 43 percent threshold with a price-based test.
Emergency contraception. CDC US Medical Eligibility Criteria, and the European Medicines Agency statement of 24 July 2014 withdrawing the weight limit.
Checked and found silent. No federal agency publishes the 28/36 ratios, a 4 percent withdrawal rate, a salary multiple for house prices, a land loan rate spread, or a national minimum roof slope. No game publisher documentation exists for Diamond Dynasty PXP values. Those are conventions, research findings and community measurements rather than published guidance.

Scope note. Rates and figures on this page were current on 18 August 2026 and change on their own schedules: market rates weekly or daily, deposit averages monthly, tax and benefit limits annually, codes every few years and only where adopted. Nothing here is financial, tax, legal, medical or veterinary advice. Program rules, tax treatment, building codes and clinical guidance vary by state and by institution, and a decision of any size is worth putting to a professional who can see your whole situation.