Calculate body fat percentage using the US Navy circumference method. Enter waist, neck, height, and hip measurements. Health data never leaves your device — every calculation runs locally in your browser.
Calculate your waist-to-hip ratio and assess health risk based on your measurements and gender. Health data never leaves your device — every calculation runs locally in your browser.
Estimate body fat percentage from BMI with an age and gender adjustment. Enter BMI, age, and gender for a quick estimate. Health data never leaves your device — every calculation runs locally in your browser.
Computes Body Mass Index from metric or imperial height and weight inputs, categorizing the result into underweight, normal, overweight, and obese, with a healthy weight range for your height. Health data never leaves your device — every calculation runs locally in your browser.
Calculate the percentage difference between any two numbers. Useful for comparing data sets, prices, and measurements. Numbers never leave your device — every calculation runs locally in your browser.
Calculate triangle area three ways — base and height, three sides (Heron), or two sides plus included angle. Pick the method matching your knowns. Numbers never leave your device — every calculation runs locally in your browser.
It uses circumference measurements (waist, neck, hips) and height to estimate body fat percentage using formulas developed by the US Navy. It's a reliable non-caliper method. Worked example — the Fit Male preset (175 cm, waist 80 cm, neck 40 cm) computes 495 ÷ (1.0324 − 0.19077 × log10(40) + 0.15456 × log10(175)) − 450 ≈ 11.1%, which lands in the Athletes band.
For men: waist and neck circumference. For women: waist, neck, and hip circumference. All measurements should be taken at the narrowest point.
Estimates typically land within a few points of DEXA results for average builds — useful for general fitness tracking, not for clinical diagnosis.
Essential fat (2-5% men, 10-13% women), athletes (6-13% men, 14-20% women), fitness (14-17% men, 21-24% women), acceptable (18-24% men, 25-31% women), obese (25%+ men, 32%+ women). The tool applies these band edges directly: under 6/14/18/25 for men and under 14/21/25/32 for women.
No. All calculations run locally in your browser. No body measurements are transmitted.
Body Fat Estimator
Estimate body fat percentage from BMI with an age and gender adjustment. Enter BMI, age, and gender for a quick estimate. Health data never leaves your device — every calculation runs locally in your browser.
Lean Body Mass Calculator
Estimate lean body mass from weight and height with Boer and James formulas averaged — the number training actually moves. Track muscle, not just scale weight — free, local, informational only.
Waist-to-Hip Ratio Calculator
Calculate your waist-to-hip ratio and assess health risk based on your measurements and gender. Health data never leaves your device — every calculation runs locally in your browser.
Last updated October 2026