About Chalk Calculator

Chalk Calculator is a collection of 30 calculators for the things people actually need to work out — a paycheck, a mortgage payment, how much gravel fills a driveway, whether a lease beats buying. They are free, they need no account, and they open fast on a phone.

What we optimise for

Accuracy first, then trust, then usability. Those come before search rankings and before advertising, and when they conflict, the ranking loses. A beautiful calculator that gives the wrong answer is a failed product.

In practice that means three habits. Every formula is documented on the page that uses it. Every assumption is listed where you can see it and change it. And where a result depends on something we cannot model reliably, the calculator says so instead of guessing.

Where the numbers come from

Tax figures come from the IRS revenue procedure for the relevant year, read from the primary document rather than a secondary summary. Payroll tax figures come from the Social Security Administration and the IRS. Inflation data is the Bureau of Labor Statistics CPI-U series, pulled directly from their public API. Employment rules come from the Department of Labor.

Where a figure is a convention rather than a published rule — the density of crushed stone, the coverage of a gallon of paint — it is an editable input with a typical default and a note explaining that your supplier or your paint can is the better authority.

Every calculator page lists its sources, its methodology version and the date it was last reviewed. The methodology page explains the process in more detail.

What we do not do

• We do not ask you to create an account, and there is nothing to sign up for.
• We do not store what you type. Calculations run in your browser; no salary, balance or debt figure is sent anywhere. See the privacy page for how that is enforced.
• We do not put your inputs in a URL, which is why there is a copy button rather than a share link.
• We do not publish near-duplicate pages to chase keywords. One good page per genuine question.
• We do not claim precision we have not implemented — see the paycheck calculator’s state coverage.

How this is paid for

Advertising, eventually. Ad slots are designed into the layout below the results, never between you and the answer, and never anywhere they could be mistaken for a control. Nothing is sold, no leads are collected, and there are no affiliate links inside the calculators.

This is not professional advice

Chalk Calculator produces estimates. It is not a tax adviser, a financial adviser, a lender, a licensed engineer or a roofer. For decisions with real consequences — a tax filing, a mortgage application, a structural question — use these tools to understand the shape of the problem, then talk to someone qualified and accountable.