About NumberBench

NumberBench is a growing library of free, no-nonsense calculators for money, home projects, health, business, and manufacturing decisions. Each tool answers one question clearly, shows the formula behind the result, and works instantly on any device.

What we believe

A good calculator should be fast, transparent, and private. Every NumberBench tool runs entirely in your browser — your inputs are never sent to us or stored — and each one explains how it reached its answer with a plain-English formula, a worked example, and notes on common mistakes.

How we build and review

Our calculators use standard, documented formulas and sourced data. State income-tax tools use the latest published brackets from the Tax Foundation; finance tools use standard time-value-of-money math; health tools use established equations. We review rate-sensitive data at least once a year. Read our full methodology and review process.

How NumberBench is funded

The tools are free. We keep them that way through advertising and the occasional affiliate recommendation for products we think are genuinely useful — see our privacy & affiliate disclosure. Ads and affiliate links never change a calculator’s math.

Suggest a calculator

Want a tool we don’t have yet, or spot a number that looks off? Tell us — requests and corrections shape what we build next.