Finance Tools

A calculator is only as good as the number you feed it, and the numbers these 53 tools need are published every week by agencies most people never think to check.

Mortgage calculators need a mortgage rate. Savings calculators need a deposit rate. Retirement calculators need this year's contribution limits. Most people supply those from memory, from a bank advert, or from whatever a page happened to hardcode when it was written, and then treat the output as an answer. The inputs are the whole calculation, and every one of them is published, dated and free.

These 53 calculators cover borrowing, paying, saving, investing and the awkward specialist cases. Below the list is the reference layer: the current figure for every rate and limit these tools depend on, each with the body that publishes it and the date it applies to. There is also one correction worth reading before you use any debt calculator, because the threshold nearly everyone quotes was removed from federal rules years ago.

Every rate and limit these calculators need, with its source and its date

Rates move. This table carries the date each figure applies to precisely so you can see when it has gone stale, which is something most calculator pages never let you do.

Borrowing

Saving

Deposit figures are the FDIC national averages across all insured institutions, which are deliberately not the best rates available. They are the floor of the market rather than the middle of it, and a competitive account will pay several times the savings average shown here. Use them to sanity-check an offer, not as an expected return.

Limits for 2026

Contribution limits apply to the 2026 tax year and are adjusted annually. Loan limits apply to loans originated in 2026. All figures were current on 17 August 2026; see section 06 for how quickly each one goes out of date.

The number these tools give you is smaller than the number you will actually pay

Every loan payment calculator, including ours, computes principal and interest. That is the arithmetic of the loan itself, and for a car or a personal loan it is close to the whole story. For a house it is not, and the gap is large enough to change what you can afford.

1. Property tax. Set locally, varies enormously, and usually collected monthly into escrow alongside the loan payment. In a high-tax county this can add hundreds a month to a payment the calculator said was affordable.
2. Homeowners insurance. Required by every lender, also escrowed, and rising sharply in parts of the country exposed to weather risk. Get a real quote for the specific address rather than an assumption.
3. Mortgage insurance. Applies on conventional loans with less than 20 percent down and on FHA loans. It is a genuine monthly cost that disappears from the calculation entirely if the calculator does not ask about your down payment. VA loans are the notable exception: they charge a one-off funding fee and no monthly mortgage insurance at all.
4. Association dues. Not part of the loan, not escrowed, and mandatory where they apply. A condo with modest dues can cost more monthly than a house with a larger mortgage.
5. Maintenance. Never in any calculator, because nobody can quote it, and reliably the largest surprise for a first-time owner.

A worked illustration of the gap

Take a loan the calculator says costs 2,000 dollars a month in principal and interest. Add a property tax bill of 4,800 dollars a year, which is 400 a month. Add insurance at 1,800 a year, which is 150. If the down payment was under 20 percent, add mortgage insurance. The payment that the calculator described as 2,000 is now comfortably over 2,550 before a single repair, and the two additions that did most of the damage are both public information you could have looked up in advance.

None of those figures is a prediction. County assessors publish tax bills for individual parcels, and an insurance quote for a specific address takes one phone call. The reason the gap surprises people is not that the information is hidden. It is that the calculator did not ask, so nobody went and got it.

This is also why the affordability question and the approval question separate. A lender includes taxes and insurance when it assesses you, because it is going to collect them. A payment calculator does not, because it is only modelling the loan. That single difference explains most of the distance between what a tool tells you a house costs and what a lender says you can borrow.

Growth calculators do not predict the future, they compound one guess for thirty years

Any tool that projects a balance forward asks you for a rate of return and then applies it, unchanged, every year until the end. That is the only way the arithmetic can work, and it is nothing like how any real investment behaves. Understanding this properly is the difference between using a projection and believing one.

Two consequences matter.

Small changes in the assumed rate produce enormous changes in the result. Compounding is multiplicative, so a rate that is one point optimistic does not make the answer slightly wrong over thirty years, it makes it substantially wrong. The output looks equally precise either way, down to the dollar, which is what makes it persuasive. The precision belongs to the arithmetic, not to the forecast.

The order of returns matters and the model ignores it. A steady average and a volatile path with the same average produce identical balances while you are contributing, and very different outcomes once you start withdrawing. Poor years early in retirement do damage that good years later cannot undo, because you sold assets to live on while they were down. No standard calculator models this.

Fees are the other thing the rate does not tell you

A quoted interest rate describes the cost of the borrowed money and nothing else. The annual percentage rate is the figure that folds in the fees a lender charges to originate the loan, which is why it is nearly always higher than the rate and why it is the one lenders are required to disclose. Two loans at the same rate with different fees are not the same loan, and the calculator that only asked you for a rate cannot see the difference.

The same distinction runs the other way on savings. A quoted rate describes what is paid before compounding; the annual percentage yield includes the effect of interest earning interest within the year. For a savings account paying monthly the gap is small. For anything paying more often, or over a long horizon, it is not, and a projection built from the rate rather than the yield will run low.

So when a calculator asks for a percentage, the useful question is which percentage it wants. Loan tools generally want the rate and then apply fees separately if they ask about them at all. Savings tools generally want the yield. Feeding one where the other belongs produces an answer that is wrong in a direction you will not notice.

The same logic, applied to the volatile ones

Several tools here project assets with no long track record or with extreme historical volatility. The arithmetic is identical and the assumption is doing even more work, because there is less history to anchor a reasonable rate to. That does not make the tool useless. It makes the output a scenario rather than a projection, and worth labelling as one in your own head before you plan around it. The bitcoin retirement calculator and the SCHD dividend calculator both sit in this category, at opposite ends of it.

Several of these answer nearly the same question from opposite directions

The most common way to waste time on a page like this is to open the wrong calculator and get a technically correct answer to a question you were not asking. Five pairs account for most of it.

Affordability against approval, which is the important one

These two get conflated constantly and they are genuinely different questions. An affordability calculator asks what payment fits your life. A debt-to-income calculator produces the ratio a lender uses to decide whether to lend at all. They can disagree in both directions, and each disagreement is informative.

Being approved for more than you can comfortably carry is the common case, because underwriting looks at your obligations rather than your groceries, your childcare or your commute. Being comfortable with more than you are approved for happens too, usually because of a short credit history or self-employment. In both situations the useful move is to run both tools and then treat the lower number as the real one.

When to use a state calculator instead of the national one

The six state mortgage tools exist because the national calculator cannot know your property tax rate, and property tax is the largest of the costs section 03 describes. Where a state has unusual property taxes or insurance costs, the state tool starts from an assumption much closer to reality.

The rule of thumb: use the national mortgage calculator to compare loans against each other, because the taxes are the same whichever loan you pick and they cancel out. Use a state calculator when you want the actual monthly figure to plan around. And use neither as final, because tax is assessed on a specific parcel and the assessor publishes it.

All 53 finance calculators, grouped by the decision you are making

The list above runs newest first. These groups follow the question rather than the tool, because several of these calculators answer nearly the same question from different directions and picking the right one saves more time than using any of them well.

Questions about using these tools, with the source named