How we build our calculators

What we’re after

A good calculator doesn’t just give you a number. It shows you how it got there. That’s why every calculator on this site shows the formula it uses, a plain-English explanation and a fully worked example.

The pages are simple on purpose: the calculator is at the top, the result updates as you type, and you never need to sign up.

Who runs this site

CalcAnswers is run by WellTracked LLC, a small company in the United States. The contact page explains how to reach us.

Where the formulas come from

We use established formulas from math, finance and medicine, along with rules set by law or by agencies such as the IRS and the Department of Labor. The sources are listed at the bottom of each page so you can look them up yourself.

How we check every calculator

Every calculator has a set of test cases: inputs whose answers were worked out separately from the calculator, for example from the formula and examples in the cited sources, from the text of a rule or from an independent calculation. Each time we publish, the software reruns every test case and compares the results, with a small tolerance for rounding. If a result doesn’t match, nothing is published.

On top of that, the math is checked a second time, either by a separate implementation or by a second AI reviewer that never sees the program code. Texts and calculation logic are written with the help of AI tools, and only what passes these checks is published.

Your data

Every calculation runs right in your browser. What you type into a calculator is not sent to us and is not stored. The privacy policy has the details.

Limits

The calculators give estimates based on the formulas shown. For binding answers about taxes, payroll, loans, contracts or your health, talk to a qualified professional.

If you spot a mistake, use “Report a problem” on the calculator’s page. We look at every report.