How we check our formulas

Every calculator on this site was AI-generated, then put through the same five-step pipeline before it went live. No competitor publishes this — we do, because the honest version of the process is a better claim than an inflated one.

The pipeline

1. Source lookup. The formula is sourced from a named authority — a government tax schedule, an engineering standard, a peer-reviewed reference, or a well-established mathematical identity. That source and the date it was checked are recorded on the calculator itself.
2. AI review. A second AI agent (Fable 5.1) independently reviews the formula, worked example, and edge cases against the cited source.
3. Golden-value test assertions. Every calculator has hand-written test cases with known-correct inputs and outputs, run automatically (npm run test:calc) on every change. A calculator that fails its own tests doesn't ship.
4. Human spot-check. A person reviews the formula, the source, and the edge cases before publication.
5. Source and date, on every page. Each calculator shows exactly what it was checked against and when — so you can judge the source yourself instead of taking our word for it.

What this is not

This is not the same claim as "hand-checked" or "human-verified" end to end — those would mean a person independently re-derived every formula from scratch, which isn't what happened here. AI-generated, AI-reviewed, automatically tested, and spot-checked by hand is a different — and more accurate — claim. A calculator that has genuinely been reviewed line by line by a person says so explicitly on that page.

Statutory calculators change

India's tax and statutory calculators (income tax, GST, HRA, EPF, and similar) are re-checked every year after the Union Budget, since the rules they encode change on a fixed schedule.

What we track

No cookies, no account, no ad network. The only measurement on this site is Cloudflare's cookieless page-view counter — it doesn't identify you or follow you anywhere else. "No tracking" would overstate that, so we say "no cookies" instead.

Something looks wrong?

Use the "Was this helpful?" control on any calculator, or see the Editorial Standards page for how corrections are handled.