Calculation Methodology

Last updated: July 26, 2026

How we implement, test, and document calculator logic.

Implementation

All calculators run client-side in JavaScript/TypeScript. Logic lives in dedicated engine modules under src/lib/tools/ and is unit-tested where applicable.

Formulas & sources

We use widely accepted formulas (e.g., Mifflin-St Jeor for BMR, standard amortization for loans, WHO BMI categories). Each tool page lists sources and references.

Rounding & display

Results are rounded for readability. Currency shows 2 decimal places; percentages typically 1–2 decimals. Internal calculations use full floating-point precision before display rounding.

Assumptions you control

Interest rates, Nisab prices, exchange rates, and activity levels are entered by you — The Daily Tools does not fetch live market or commodity data.

Questions? See Sources Policy or Contact.