Body Fat Calculator
Estimate body fat percentage using only a tape measure. This calculator uses the US Navy method with your neck, waist, height and, for women, hip. Add your weight to see fat mass and lean mass. It runs in your browser.
Runs in your browser. Your files are never uploaded.
Loading Body Fat Calculator…
How to use Body Fat Calculator
- Choose male or female and cm or inches.
- Enter height, neck and waist. Women also enter hip.
- Optionally enter your weight to see fat mass and lean mass.
- Read your body fat percentage and category.
The US Navy method
The method estimates body density from circumference measurements using logarithms. For men it uses waist minus neck and height. For women it uses waist plus hip minus neck, and height. Density is then converted to a body fat percentage.
ACE categories
- Men: essential fat 2 to 5 percent, athletes 6 to 13, fitness 14 to 17, average 18 to 24, obese 25 and above.
- Women: essential fat 10 to 13 percent, athletes 14 to 20, fitness 21 to 24, average 25 to 31, obese 32 and above.
Getting a steady reading
Measure at the same time of day, standing relaxed, with the tape level and not pressing into the skin. Take each measurement twice and use the average. Small measuring errors can move the result noticeably.
Limits
This is an estimate only and not medical advice. The method suits adults and may be less accurate for very muscular, very lean or older people, and during pregnancy. Calculation happens in your browser and nothing is uploaded.
Why use this body fat calculator tool
- Tape measure only. No scale or calipers needed. The US Navy method uses neck, waist and height, plus hip for women.
- Category shown. See whether the result is essential fat, athlete, fitness, average or obese, using ACE ranges for your sex.
- Fat and lean mass. Add your weight to split it into fat mass and lean mass in kg and lb.
- Checks your input. Impossible measurements, such as a waist smaller than the neck, give a clear message instead of a wrong number.
Frequently asked questions
How do I measure myself for the US Navy method?
Stand relaxed. Measure the neck just below the larynx, the waist at the navel (keep the tape level), and the hip at the widest point. Keep the tape snug but not tight.
How accurate is the US Navy body fat method?
It is an estimate and is often a few percentage points off compared with methods like DEXA scans. It works best for comparing yourself over time using the same way of measuring each time.
What is a healthy body fat percentage?
Using ACE categories, men are roughly 14 to 24 percent in the fitness to average range, and women about 21 to 31 percent. Healthy ranges depend on age and goals, so ask a professional for personal advice.
Why does it say my waist must be larger than my neck?
The formula uses the difference between waist and neck, and cannot work if the waist is not larger. This usually means a measurement or unit was entered incorrectly, so check the numbers and the cm or inches setting.
Is my data uploaded?
No. Everything is calculated in your browser, and your measurements are never sent or stored.
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