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Both calculators run independently — change the inputs on either side to compare results.

Health

Body Fat Percentage Calculator

Estimate your body fat percentage from a tape measure using the US Navy circumference method — the same protocol the US military uses for fitness compliance. Enter your waist, neck, height (and hip if female) and the calculator returns body fat percentage, accurate to within ±3–4 percentage points compared to a DEXA scan.

Fill in the required fields to see your result.
Fitness

BMI Calculator

Calculate Body Mass Index (BMI) — body weight in kg divided by height in metres squared — to screen for under/overweight categories. The most widely used population-level fitness and health risk metric, with known limitations for athletes and unusual body compositions.

Underweight<18.5Normal18.5–25Overweight25–30Obese I30–35Obese II+35+
Fill in the required fields to see your result.

Key differences

Body Fat Percentage CalculatorBMI Calculator
CategoryHealthFitness
Inputs required32
ResultBody Fat Percentage (%)Your BMI
What it doesEstimate your body fat percentage from a tape measure using the US Navy circumference method — the same protocol the US military uses for fitness compliance. Enter your waist, neck, height (and hip if female) and the calculator returns body fat percentage, accurate to within ±3–4 percentage points compared to a DEXA scan.Calculate Body Mass Index (BMI) — body weight in kg divided by height in metres squared — to screen for under/overweight categories. The most widely used population-level fitness and health risk metric, with known limitations for athletes and unusual body compositions.