Body fat
calculator.
Estimate your body fat percentage with a tape measure: height, neck and waist, plus hips for women. No scale or gym equipment needed.
Neck below the Adam's apple. Waist at the navel for men, at the narrowest point for women. Hips at the widest point.
Fill in the form to see your result.
Track it every day. Luntrack uses this exact method and adjusts as your weight and training change.
The method,
in plain words.
The US Navy method
It estimates body fat from body measurements. For men: 495 / (1.0324 − 0.19077 × log10(waist − neck) + 0.15456 × log10(height)) − 450. For women the hips are added to the waist and the constants change.
How to measure
Use a soft tape on bare skin, snug but not pressing. Neck just below the Adam's apple. Waist at the navel for men and at the narrowest point for women. Hips at the widest point. Measure in the morning and take the average of two tries.
Fat mass and lean mass
If you add your weight, your weight times the percentage is your fat mass. Everything else, muscle, bone, organs and water, is lean mass.
The categories
Ranges from the American Council on Exercise. Men: essential fat 2 to 5%, athletes 6 to 13%, fitness 14 to 17%, average 18 to 24%. Women: essential 10 to 13%, athletes 14 to 20%, fitness 21 to 24%, average 25 to 31%.
For general fitness guidance only — not medical advice. If you're pregnant, have a medical condition or take medication that affects appetite or fluids, check with a doctor first.
Good questions.
How accurate is the US Navy method?
For most people it lands within about 3 to 4 percentage points of a DEXA scan. The biggest source of error is the tape, so measure the same way every time and watch the trend rather than one number.
Is it better than BMI?
For people who train, yes. BMI only looks at height and weight, so muscular people often show as overweight. Waist and neck measurements say more about where the weight sits.
How often should I measure?
Every two to four weeks is enough. Body fat changes slowly, and day to day water and food in your stomach move the tape a little.
What is a healthy body fat percentage?
For most men 14 to 24% and for most women 21 to 31% is a healthy range. Going below essential fat is not healthy for anyone.