Methodology
Every formula we use, the sources we cite, and the assumptions we make. E-E-A-T grade transparency: no black boxes.
Trust requires transparency. This is the page for anyone who wants to know HOW our calculators work — not just the answer, but the formula, the steps, the authoritative sources, and the limitations. Each methodology page is reviewed quarterly by our editorial team.
How we calculate BMI
weight ÷ height² · Last reviewed 2026-06-15
Open the calculator →How we calculate mortgage payments
P × r(1+r)ⁿ ÷ ((1+r)ⁿ − 1) · Last reviewed 2026-06-15
Open the calculator →How we calculate compound interest
A = P × (1 + r/n)^(n × t) · Last reviewed 2026-06-15
Open the calculator →How we calculate percentages
(part ÷ whole) × 100 · Last reviewed 2026-06-15
Open the calculator →How we calculate loan payments
P × r(1+r)ⁿ ÷ ((1+r)ⁿ − 1) · Last reviewed 2026-06-15
Open the calculator →How we calculate tips
tip = bill × (tip% ÷ 100) · Last reviewed 2026-06-15
Open the calculator →How we calculate ROI
(gain − cost) ÷ cost × 100 · Last reviewed 2026-06-15
Open the calculator →How we compare BMI to other health metrics
(A − B) ÷ B × 100 · Last reviewed 2026-06-15
Open the calculator →How we calculate daily calorie needs
BMR × activity multiplier · Last reviewed 2026-06-15
Open the calculator →How we calculate auto loan payments
P × r(1+r)ⁿ ÷ ((1+r)ⁿ − 1) · Last reviewed 2026-06-15
Open the calculator →How we calculate salary conversions
hourly × hours per year · Last reviewed 2026-06-15
Open the calculator →How we calculate area
Shape-specific · Last reviewed 2026-06-15
Open the calculator →Browse all methodology pages: 12 calculators • Last reviewed: June 15, 2026