Body Fat Calculator
Estimate your body fat percentage using the U.S. Navy tape method. Enter your measurements in inches. This is a general estimate, not a medical or clinical body-composition test.
Example: with Age 30 yrs · Weight 180 lb · Height 5 ft · Neck 15 in → Body fat: 17.5%.
- Body Fat Mass31.5 lb
- Lean Body Mass148.5 lb
- Ideal Body Fat for Age (Jackson & Pollock)12.7%
Computed by the calculator below using its default values. Change any input to see your own numbers.
Where you land
How you compare
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Check it outAbout the Navy method
The U.S. Navy formula estimates body fat from a few tape measurements: neck and waist for everyone, plus hips for women, all relative to height. It's free and surprisingly consistent, but it's an estimate — not as precise as a DEXA scan or calipers in trained hands. Measure snugly and consistently, and treat results as a trend rather than an exact figure. This isn't medical advice. We also show a second, rougher estimate from the BMI method (using your age, sex, height and weight) so you can see how the two compare — they won't match exactly since they use different inputs.
Body fat category (American Council on Exercise)
| Description | Women | Men |
|---|---|---|
| Essential fat | 10–13% | 2–5% |
| Athletes | 14–20% | 6–13% |
| Fitness | 21–24% | 14–17% |
| Average | 25–31% | 18–24% |
| Obese | 32%+ | 25%+ |
Jackson & Pollock ideal body fat by age
| Age | Women | Men |
|---|---|---|
| 20 | 17.7% | 8.5% |
| 25 | 18.4% | 10.5% |
| 30 | 19.3% | 12.7% |
| 35 | 21.5% | 13.7% |
| 40 | 22.2% | 15.3% |
| 45 | 22.9% | 16.4% |
| 50 | 25.2% | 18.9% |
| 55 | 26.3% | 20.9% |
How it’s calculated
U.S. Navy method: body fat % from a logarithmic formula using neck, waist (and hips for women) relative to height. Body Fat Mass = body fat % × weight; Lean Body Mass = weight − Body Fat Mass. The Ideal Body Fat for Age uses the Jackson & Pollock age-based table above (interpolated between ages); Body Fat to Lose to Reach Ideal = (current % − ideal %) × weight, shown only when current is above ideal. The BMI-method estimate is a separate cross-check: BFP = 1.20 × BMI + 0.23 × age − 16.2 (adult men) or 1.20 × BMI + 0.23 × age − 5.4 (adult women).
Results update as you type and are estimates, not professional advice — verify important decisions with a qualified professional.
Sources: U.S. Navy body fat method; BMI-method and Jackson & Pollock formulas as published by public fitness references; ACE body-fat categorization.
Common mistakes
- Measuring the waist or neck in the wrong place.
- Treating an estimate like a clinical body-composition test.
Frequently asked questions
How accurate is it?
Reasonably good for tracking trends, typically within a few percent. Clinical methods like DEXA are more precise.
Where do I measure?
Waist at the navel, neck just below the larynx, hips at the widest point. Keep the tape level and snug, not tight.
Do women need the hip measurement?
Yes — the female formula requires neck, waist, and hip. Men use neck and waist only.
What's the difference between the Navy method and the BMI method?
The Navy method uses tape measurements (neck, waist, hip) and tends to track real body composition better. The BMI method only uses height, weight, age and sex, so it can misread muscular or very lean people. We show both so you can compare.
What is Lean Body Mass?
Lean Body Mass is your total weight minus your estimated fat mass — roughly your muscle, bone, organs, and water weight combined.