About ProvenCalc

ProvenCalc is an independent site of small calculators that answer one question quickly and show their work. We favor correctness, useful defaults, and plain-language limits over feature counts. The public site does not require an account, collect form submissions, or pretend an estimate is more precise than its inputs.

What we build

Every tool is hand-authored around a distinct task. The position size calculator separates cash risk from notional exposure. The drawdown recovery calculator exposes asymmetric percentage math. Our TDEE calculator, date calculator, and eSIM data estimator make their assumptions equally visible.

How a tool earns its place

We verify formulas with automated known-answer tests, keep core calculations in the browser, and cite primary or authoritative sources when the input is scientific, medical, regulatory, or device-specific. Explanations include worked examples and reference tables because a number without context is easy to misuse. Finance and health pages carry direct disclaimers rather than hiding limitations in legal copy.

We would rather have a few tools that are genuinely useful than hundreds of near-identical pages. A new calculator is added only when we can explain its formula, test it, and make it clearer than what already exists. Corrections are welcome through the contact page. Material updates change the date shown in the page footer.

How the site is funded

The site currently earns from clearly-labelled affiliate links on some tool results and may later show ads. If you buy through one of those links, we may earn a commission at no extra cost to you. Monetization never changes a formula or a result.