Calculation Methodology
Every Atlascalcs tool runs in your browser with published formulas, worked examples and cited sources. Finance figures track IRS and CFPB rules, health tools cite NIH and CDC ranges, and all engines pass automated known-answer tests. No sign-up required.
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Formula first, interface second
Each tool starts from a citable source — IRS publications and CFPB guides for finance, NIH and CDC references for health, standards and textbooks for engineering — then encodes the formula in an isolated engine with known-answer tests (boundary values, unit conversions, rounding). The page shows the formula, variables and a worked example so any result is reproducible by hand. Try it on the mortgage calculator or the BMI calculator.
Testing and update cadence
Engines run in CI on every deploy; finance, health and legal pages carry a currency marker under editorial policy with yearly figure refreshes. Confirmed errors are fixed with the next update, and every page supports embeds so third parties can re-run our numbers. Report issues via contact.