Body fat calculator
Estimate your body fat percentage with a tape measure (US Navy or Army method) or from your BMI, and see your fat mass, lean mass and category.
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Body fat
19.3%
Average
- Fat mass
- 30.9 lb
- Lean mass
- 129.1 lb
- BMI
- 25.8
- Army method
- 21.5%
- BMI method
- 21.7%
Watch it change, not just the scale
TrackAI logs your weight with a weekly trend and sets your protein to keep muscle while you lose fat. Try it free for 3 days.
The formulas
- 1
US Navy method (men). Body fat % = 86.010 × log10(waist − neck) − 70.041 × log10(height) + 36.76, all in inches. Waist is measured at the navel.
- 2
US Navy method (women). Body fat % = 163.205 × log10(waist + hip − neck) − 97.684 × log10(height) − 78.387, in inches. Waist at its narrowest, hip at its widest.
- 3
Army one-site tape (2023). Men: −26.97 − 0.12 × weight (lb) + 1.99 × waist (in). Women: −9.15 − 0.015 × weight (lb) + 1.27 × waist (in). Waist is measured at the navel.
- 4
BMI estimate. Deurenberg (1991): 1.20 × BMI + 0.23 × age − 10.8 × sex − 5.4, where sex is 1 for men and 0 for women. The roughest of the three: it cannot tell muscle from fat.
- 5
Fat and lean mass. Fat mass is body fat % × weight; lean mass is everything else (muscle, bone, organs, water).
Body fat categories
| Category (ACE) | Men | Women |
|---|---|---|
| Essential fat | 2–5% | 10–13% |
| Athletes | 6–13% | 14–20% |
| Fitness | 14–17% | 21–24% |
| Average | 18–24% | 25–31% |
| Obese | 25%+ | 32%+ |
Estimates, not a medical assessment. To lose fat and keep muscle, start with your TDEE and protein target.
Questions
How accurate is the Navy body fat calculator?
Tape methods often land within a few percentage points of a DEXA scan, though one person can be further off, and they are most useful for tracking change over time with the same tape and the same spots. Very lean or very muscular people tend to be overestimated.
How do I measure for the Navy method?
Use a soft tape, snug but not compressing the skin, and measure after breathing out normally. Neck: just below the larynx (Adam's apple), tape sloping slightly down to the front. Waist: men at the navel, women at the narrowest point. Hips (women only): at the widest point of the buttocks. Measure twice and use the average.
What is the Army body fat calculator?
Since 2023 the US Army uses a one-site tape test: only the waist at the navel plus body weight, for both men and women, replacing the old neck and hip measurements. This page uses the widely published equations from that change; for an official assessment, the Army's own worksheet and the tester's measurement are what count.
What is a healthy body fat percentage?
By the American Council on Exercise ranges, men are in the "fitness" range at 14–17% and "average" at 18–24%; women at 21–24% and 25–31%. Essential fat, the minimum the body needs, is 2–5% for men and 10–13% for women.
Why is my body fat different on a smart scale?
Smart scales use bioelectrical impedance, which shifts with hydration, food and time of day. Tape methods and scales will rarely agree on the exact number; pick one method and watch the trend.
How do I lower my body fat?
Eat a modest calorie deficit with enough protein and keep strength training, so the weight you lose is mostly fat. The TDEE and protein calculators give you the numbers to start with.