Best Fitness Calculators 2026

What makes a fitness calculator accurate and useful — and which ones to use.

What to Look For

Good calculators use established formulas (Mifflin-St Jeor for BMR/TDEE, Navy method for body fat, Epley/Brzycki for 1RM). They support metric and imperial, and don’t require sign-up.

Essential Calculators

BMI — Quick baseline. TDEE — Core for diet planning. Macro — Protein, carbs, fat split. Body fat — Navy method is convenient. 1RM — For strength programming.

Privacy Matters

Client-side calculators (like ours) run in your browser. No data is sent to servers. Your health inputs stay private.