Handy tools
Body Fat Calculator
Estimate body fat % with the US Navy tape method from height, neck and waist (plus hips for women).
Estimate your body fat percentage with the US Navy tape-measure formula (Hodgdon–Beckett). Enter your sex, height and your neck and waist circumference in cm; women also add hip circumference. Add your weight in kg to split the result into fat mass and lean mass. Made for adults 18 and over.
How to measure
- Neck: just below the Adam's apple (larynx), with the tape sloping slightly down toward the front.
- Waist: horizontally at the level of your navel, at the end of a normal breath out.
- Stand straight and relaxed and don't pull in or tense your stomach. Keep the tape snug without pressing into the skin. Measure twice and enter the average.
Fitness range — a lean level, common in people who exercise regularly.
- Body fat percentage
- 16.9 %
- Category (ACE)
- Fitness (14–17.9%)
- Fat mass
- 11.8 kg
- Lean mass (fat-free)
- 58.2 kg
Fat mass and lean mass are shown only when you enter your weight.
An estimate from the US Navy circumference formula. It is usually within about 3–4 percentage points of lab methods such as DEXA and can be further off for very muscular or very lean bodies. The formula differs by biological sex and is meant for adults, not teens or pregnancy. Not medical advice.
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The Giggleus body fat calculator estimates your body fat percentage with the US Navy circumference formula (Hodgdon and Beckett, 1984). Enter your sex, height, neck and waist in centimetres (women also enter hip circumference) and you get a percentage plus an ACE category. Add your weight in kg and it splits your body into fat mass and lean (fat-free) mass.
Example: a man who is 180 cm tall with a 40 cm neck and a 90 cm waist comes out at 18.4%, the average range; at 80 kg that is 14.7 kg of fat and 65.3 kg of lean mass. A woman who is 165 cm with a 32 cm neck, 72 cm waist and 96 cm hips comes out at 26.4%, also average.
Categories follow the American Council on Exercise (ACE) ranges for adults. Men: essential fat under 6%, athletes 6–13%, fitness 14–17%, average 18–24%, obese 25% and up. Women: under 14%, 14–20%, 21–24%, 25–31%, 32% and up. A tape-measure estimate usually lands within about 3–4 percentage points of DEXA and can miss by more for very muscular or very lean bodies. The formula is for adults, not teens or pregnancy, and the result is not medical advice.
Frequently Asked Questions
Q. How does the US Navy method calculate body fat?
A. It puts your height and circumferences into a logarithmic formula: men use waist minus neck, women use waist plus hips minus neck. For example, a 180 cm man with a 40 cm neck and a 90 cm waist gets about 18.4%.
Q. Where should I measure my neck, waist and hips?
A. Measure your neck just below the Adam's apple and your waist at navel level for men or at the narrowest point for women, both at the end of a normal breath out. Measure hips at the widest part of the buttocks. Keep the tape snug but not tight, and don't pull your stomach in.
Q. What is a healthy body fat percentage?
A. By ACE adult ranges, average is 18–24% for men and 25–31% for women, while fitness is 14–17% and 21–24%. Men at 25% or more and women at 32% or more fall into ACE's obese range. Essential fat, roughly 2–5% for men and 10–13% for women, is not a target.
Q. How accurate is a body fat calculator?
A. Expect roughly ±3–4 percentage points compared with DEXA, and more for very muscular or very lean people. It is built for adults, not teens or pregnancy, so use it to track trends rather than as a diagnosis.