Health Calculators
Track body composition, nutrition targets, and fitness metrics.
166 free calculators
Numbers That Matter for Your Body
Health calculators bridge the gap between clinical formulas and practical decisions. The same equations your doctor uses to assess metabolic rate or body composition are available here, explained in plain language so you can understand what the numbers actually mean.
Start With the Fundamentals
The BMI calculator remains the most-searched health tool online — it's imperfect as a sole indicator, but it's the standard screening metric used in clinical settings worldwide. For a more complete picture, the body fat calculator uses skinfold or measurement-based methods, and the BMR calculator tells you how many calories your body burns at rest. Together, these three tools give you a baseline for any nutrition or fitness plan.
Fitness and Training
If you're tracking workout performance, the RPE calculator converts rate of perceived exertion into estimated one-rep maxes — useful for programming strength training without testing true maxes every session. The rucking calorie calculator handles the surprisingly complex math of weighted walking, accounting for load, speed, and terrain.
A Note on Medical Calculators
These tools implement published clinical formulas accurately, but they are not a substitute for professional medical advice. Use them to understand the math behind health metrics, prepare informed questions for your provider, or track trends over time.