What is the Body Fat Calculator?
Estimate body fat percentage using the U.S. Navy circumference method. Our health and fitness calculators use validated, published equations — such as Mifflin-St Jeor for metabolic rate and the U.S. Navy method for body fat — to give you a solid starting point for training and nutrition.
How to use the Body Fat Calculator
- Enter your sex, your height, your neck, your waist and the remaining fields.
- Results update automatically as you type; you can also press Calculate.
- Read the output: body fat, fat mass, lean mass.
- Use the 📊 chart to see the result visually, then copy or share it.
Formula and method
Worked example
With sex = Male, height = 178 cm, neck = 38 cm, waist = 85 cm, hip = 95 cm, the Body Fat Calculator returns body fat: 16.4%; fat mass: 12.8 kg; lean mass: 65.2 kg.
Tips for better results
- Equations estimate population averages; your individual numbers may differ.
- Track trends over weeks rather than reacting to a single reading.
- Pair calculators with professional guidance for medical conditions, pregnancy or major diet changes.
⚠️ This tool provides general information and is not medical advice. It is not a substitute for diagnosis or treatment by a qualified healthcare professional.
Frequently asked questions
What does the Body Fat Calculator do?
Estimate body fat percentage using the U.S. Navy circumference method.
How is it calculated?
The Body Fat Calculator uses this method: Men: 495 ÷ (1.0324 − 0.19077·log(waist − neck) + 0.15456·log(height)) − 450; Women: 495 ÷ (1.29579 − 0.35004·log(waist + hip − neck) + 0.221·log(height)) − 450.
Can you show an example?
With sex = Male, height = 178 cm, neck = 38 cm, waist = 85 cm, hip = 95 cm, the Body Fat Calculator returns body fat: 16.4%; fat mass: 12.8 kg; lean mass: 65.2 kg.
Is the Body Fat Calculator accurate?
It uses standard published formulas and is tested against known values, but results are estimates for guidance. This tool provides general information and is not medical advice. It is not a substitute for diagnosis or treatment by a qualified healthcare professional.
Is this tool free and private?
Yes — the Body Fat Calculator is completely free with no sign-up, and it runs entirely in your browser, so the values you enter are never uploaded to our servers.
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