What other methods can I use if I have no tape measure?

BMI & age needs only height, weight and age, but it is less accurate. Skinfold (3-site) uses caliper readings in millimetres from chest, abdomen, thigh, triceps or suprailiac sites, depending on sex.

How accurate is the body fat estimate?

It is a statistical estimate with an error band of a few percentage points, useful for tracking trends rather than as a clinical measurement. DEXA or other clinical tests give a more accurate reading.

Can it show my fat mass and lean mass?

Yes. Enter your weight, which is optional, and the result also shows Fat mass and Lean body mass next to the estimated body fat percentage and its category, such as Fitness or Average.

Why does it warn that waist must be larger than neck?

The Navy formula uses the difference between waist (plus hip for women) and neck, which must be positive. This warning usually means a measurement was entered in the wrong place or the wrong unit.

Yes. Every tool is free to use, with no account and no credit card. The work runs on your device rather than on our servers, which is what keeps it free to run.

Does it work on mobile?

Yes. It runs in current mobile browsers on iOS and Android, with nothing to install.

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Free Body Fat Calculator

Q: How do I measure myself for the U.S. Navy body fat method?

Choose U.S. Navy (tape measure), enter your height, then measure your neck just below the larynx and your waist at the navel, relaxed, with a snug tape. Women also enter Hip.

Estimate your body-fat percentage with the U.S. Navy tape-measure method or a BMI-and-age estimate — with your fitness category, fat mass, and lean body mass. Metric or imperial, private and free.

Runs in your browserNo sign-up, no pop-upsNo login requiredFree foreverU.S. Navy tape methodFat + lean mass

Works offline once loaded

Estimate your body-fat percentage from a few tape-measure circumferences (U.S. Navy method) or from your BMI and age. Everything is calculated privately in your browser.

Sex

Units

Height

Neck

Waist

Measure your neck just below the larynx and your waist at the navel, relaxed, with a snug tape.

Weight (optional)

Estimated body fat

18.7%

Average

Fat mass15 kg

Lean body mass65 kg

⚠️ Body-fat percentage here is a statistical estimate with a few-percent error band — useful for tracking trends, not a clinical measurement. It is not medical advice and does not apply to children or during pregnancy. For an accurate reading, see a healthcare provider.

🔒 Your measurements never leave your device — everything is calculated in your browser.

Common uses

U.S. Navy Body Fat CalculatorEstimate body fat with the U.S. Navy circumference method — just a tape measure, no calipers.
Body Fat Percentage CalculatorCalculate your body-fat percentage and see your fitness category.
Lean Body Mass CalculatorEnter your weight to split it into fat mass and lean body mass.
Body Fat Calculator for MenEstimate body fat for men using neck and waist measurements.
Body Fat Calculator for WomenEstimate body fat for women using neck, waist and hip measurements.
BMI to Body Fat EstimateNo tape measure? Estimate body fat from your BMI and age.

How It Works

Estimates your body-fat percentage with the U.S. Navy (Hodgdon–Beckett) circumference method — which needs only a tape measure — or a BMI-and-age estimate when you don't have measurements. Add your weight to split it into fat mass and lean mass. Everything is computed in your browser.

1
Pick a method
The U.S. Navy method uses your height, neck and waist (plus hip for women). The BMI method needs only height, weight and age, but is less accurate.
2
Choose sex and units
The formulas use sex-specific terms. Switch between metric (cm / kg) and imperial (in / lb) at any time.
3
Measure and enter
Measure your neck below the larynx and your waist at the navel, relaxed, with a snug tape. Enter the values and your height.
4
Read your result
You get an estimated body-fat percentage, the fitness category, and — if you enter a weight — your fat mass and lean body mass.