📉 Body Fat Calculator
Estimate body fat percentage with the U.S. Navy method using circumference measurements — gender, height, neck, waist (and hip for women). All in your browser.
Enter your measurements to estimate your body fat percentage.
About the Body Fat Calculator
This calculator estimates body fat percentage using the U.S. Navy circumference method. It is widely used because it requires only a tape measure and gives a reasonable estimate without specialized equipment. All math runs in your browser; nothing leaves your device.
Formulas (U.S. Navy method, centimetres)
- Male:
BF% = 495 / (1.0324 − 0.19077 × log10(waist − neck) + 0.15456 × log10(height)) − 450 - Female:
BF% = 495 / (1.29579 − 0.35004 × log10(waist + hip − neck) + 0.22100 × log10(height)) − 450
Body fat categories (ACE)
- Essential fat — Men 2–5%, Women 10–13%.
- Athletes — Men 6–13%, Women 14–20%.
- Fitness — Men 14–17%, Women 21–24%.
- Average — Men 18–24%, Women 25–31%.
- Obese — Men ≥25%, Women ≥32%.
How to use
- Select your gender.
- Enter height, neck, and waist in centimetres. Women also enter hip.
- Click Calculate. The estimated body fat percentage and category appear below.
Frequently asked questions
How accurate is the Navy method? It typically estimates body fat within 3–4% of more accurate methods like DEXA scans. It is a useful tracking tool but not a clinical measurement.
How should I measure waist? Measure at the navel, relaxed, after exhaling. Keep the tape horizontal and snug but not compressing skin.
Why is hip needed for women? The Navy method accounts for fat distribution differences between sexes; women tend to store more fat around the hips.
Can I use inches? This calculator accepts centimetres only. Convert inches to centimetres (1 inch = 2.54 cm) before entering.