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Body Fat Calculator
Estimate your body fat percentage with nothing more than a tape measure, using the US Navy circumference method. Enter your height, neck and waist — and hips if you are a woman — plus your weight to split it into fat mass and lean mass.
- ACE category
- Fitness
- Fat mass
- 31.4 lb
- Lean mass
- 148.6 lb
Saved setups
Save a set of inputs you reuse — your usual rate, your loan, your room sizes — and load it back in one tap.
Your recent calculations
Results you calculate here are kept on this device so you can come back to them.
Formula
How to use it
- Select your sex and enter your height and weight.
- Measure your neck just below the larynx, keeping the tape level.
- Measure your waist — at the navel for men, at the narrowest point for women — and, for women, the hips at their widest.
- Read your estimated body fat percentage, category, fat mass and lean mass.
Worked examples
A man 5 ft 10 in and 180 lb with a 15 in neck and 34 in waist
- Body fat
- 17.4%
- ACE category
- Fitness
- Fat mass
- 31.4 lb
- Lean mass
- 148.6 lb
A woman 5 ft 5 in and 140 lb with a 13 in neck, 30 in waist and 38 in hips
- Body fat
- 28.3%
- ACE category
- Average
- Fat mass
- 39.6 lb
- Lean mass
- 100.4 lb
How good is the Navy method
The equations were developed by Hodgdon and Beckett at the Naval Health Research Center in 1984. For most people they land within about 3 to 4 percentage points of laboratory methods such as underwater weighing or DEXA. Small tape errors matter: half an inch on the waist moves the result by roughly one point, so measure twice and take the average.
Category labels
The category shown uses the widely reproduced American Council on Exercise chart. Women: essential fat 10–13%, athletes 14–20%, fitness 21–24%, average 25–31%, obese 32% and above. Men: essential fat 2–5%, athletes 6–13%, fitness 14–17%, average 18–24%, obese 25% and above.
This is an estimate for general information, not medical advice. Talk to a doctor or other qualified clinician before making health decisions based on it.
Questions people ask
What is a healthy body fat percentage?
On the American Council on Exercise chart, the fitness and average bands run from 14% to 24% for men and 21% to 31% for women. Women naturally carry more essential fat than men.
How do I measure body fat at home?
With a flexible tape. A man 5 ft 10 in tall with a 15 in neck and 34 in waist comes out at about 17.4% by the Navy method; at 180 lb that is about 31 lb of fat and 149 lb of lean mass.
Why do women need a hip measurement?
Women store more fat around the hips and thighs, so the women’s equation adds hip circumference to capture it. The men’s equation uses only waist and neck.