Fitness & Body Composition Calculators
Measure and track your body composition with evidence-based calculators for BMI, body fat percentage, ideal weight, and more. Based on formulas validated against DEXA and clinical measurements.
8 free toolsArmy Body Fat Calculator
Estimate your body fat percentage using the U.S. Army tape test method. Based on gender, age, height, neck, and waist measurements.
Calculate Body Fat →
Ideal Body Weight Calculator
Calculate your ideal body weight range based on height, gender, and frame size using multiple evidence-based formulas.
Calculate Weight →
Creatine Hydration Calculator
Calculate optimal water intake when using creatine supplements.
Calculate Hydration →
BMI Calculator
Calculate your Body Mass Index and see your weight category based on WHO guidelines. Includes healthy weight range for your height.
Calculate BMI →
Calories Burned Calculator
Calculate calories burned during exercise and daily activities using MET values from the Compendium of Physical Activities for 30+ exercises.
Calculate Calories Burned →
Body Fat Calculator
Calculate your body fat percentage using the U.S. Navy method. Simple neck, waist, and hip measurements give accurate body composition estimates.
Calculate Body Fat →
Body Roundness Index (BRI)
Calculate your Body Roundness Index using waist circumference and height. BRI measures central adiposity and predicts health risk more accurately than BMI.
Calculate BRI →
Metabolic Age Calculator
Calculate your metabolic age by comparing your BMR to population averages. Find out if your metabolism is younger or older than your actual age.
Calculate Metabolic Age →
Beyond the Scale: Measuring What Matters
Bodyweight alone tells an incomplete story. Two people at the same weight can have vastly different body compositions — and very different health risk profiles. These calculators help you understand what your body is made of, not just how much it weighs.
Which Calculator Should You Start With?
- BMI Calculator — Quick screening tool using just height and weight. Good starting point but has known limitations for athletes and muscular individuals
- Body Fat Calculator — Uses the U.S. Navy circumference method for a more accurate picture of body composition. Requires a tape measure
- Body Roundness Index — Newer metric that captures central adiposity (belly fat) specifically, which is the strongest predictor of metabolic disease risk
- Ideal Body Weight — Compares multiple evidence-based formulas (Devine, Robinson, Miller, Hamwi) to give you a realistic target range
Tracking Progress Over Time
Body composition changes slowly. Measure under consistent conditions (same time of day, same hydration state) and track trends over weeks, not daily fluctuations. A 1-2% change in body fat percentage per month is excellent progress.