Body Fat Calculator
Estimate body fat percentage from height and neck, waist and hip measurements with the US Navy method.
Your measurements
Filled in with example values. Replace them with your own.
Measurements
Use a soft tape measure, snug but not pressing into the skin, and measure on bare skin after breathing out normally. Small errors in a measurement change the result noticeably, so measuring twice helps.
Optional
Shows the estimate as fat mass and lean mass.
Results update as you type.
Result
Body fat (US Navy method): about 16.1%
Estimated body fat
16.1%
An estimate, not medical advice. The tape-measure method gives an estimate that can differ noticeably from a body scan, and more so if a measurement is slightly off. It does not show where fat is stored or say what is healthy for you. For that, talk to a doctor.
How it’s calculated
Waist − neck
85 cm − 38 cm = 47 cm
Body fat
495 ÷ (1.0324 − 0.19077 × log10(85 cm − 38 cm) + 0.15456 × log10(180 cm)) − 450 = 16.1%
Important
This calculator gives a general estimate from a published formula. It is not a diagnosis and not medical advice, and it cannot take your health, medicines or history into account. Body fat from tape measurements is an estimate and can be off, especially if a measurement is taken in the wrong place.For advice about your weight, diet or health, talk to a doctor or a registered dietitian. See theDisclaimer.
How the body fat calculator works
The calculator uses the US Navy circumference method, published by Hodgdon and Beckett in 1984. It estimates body fat from your height and the circumference of your neck and waist, and for women also the hips.
If you add your weight, the percentage is turned into fat mass and lean mass.
How to measure
- Neck: just below the larynx (Adam’s apple), with the tape sloping slightly down to the front.
- Waist, men: around the belly at the level of the navel.
- Waist, women: at the narrowest point, usually a little above the navel.
- Hips, women: at the widest point of the buttocks.
Measure on bare skin, with the tape snug but not pressing in, after breathing out normally.
The formula
Men:
495 ÷ (1.0324 − 0.19077 × log10(waist − neck) + 0.15456 × log10(height)) − 450
Women:
495 ÷ (1.29579 − 0.35004 × log10(waist + hips − neck) + 0.22100 × log10(height)) − 450
All measurements in centimetres. Fat mass = weight × body fat %.
Worked examples
- A man, 180 cm tall, neck 38 cm, waist 85 cm: waist − neck = 47 cm, giving about 16.1%. At 80 kg, that is about 12.9 kg of fat.
- A woman, 165 cm tall, neck 32 cm, waist 72 cm, hips 98 cm: waist + hips − neck = 138 cm, giving about 27.4%.
Limitations
- An estimate from body shape, not a measurement of fat. Small measuring errors change the result noticeably.
- It was developed from adults and may suit some body types less well than others.
- It does not show where fat is stored, and it is not meant for children or during pregnancy.
Frequently asked questions
How accurate is the tape-measure method?
It is an estimate based on how body shape relates to body fat in the people the formula was developed from. It is useful for following changes over time with the same tape and technique, but it can differ noticeably from methods such as a DEXA scan, especially for people whose shape differs from that group.
What is a healthy body fat percentage?
There is no single agreed standard. Different organisations publish different ranges, which also vary with age and sex, so this calculator does not label the result. A doctor can tell you what makes sense for you.
Why does my result differ from another calculator using the Navy method?
The method has a metric form and an inch form whose constants were fitted separately, so they give slightly different answers. This calculator uses the metric form and converts inches exactly (1 in = 2.54 cm). Rounding of the measurements also matters.
Why do women need a hip measurement?
The formula for women was fitted using the waist, hips and neck, because body fat is distributed differently on average. The formula for men uses only the waist and neck.