Health

Navy Body Fat Calculator

Estimate your body fat percentage using the US Navy circumference method. Enter neck, waist, and height (plus hip for women) — no calipers needed.

Biological Sex

Measurement Unit

Enter your measurements to see the result.

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Navy Method Formulas

All measurements are converted to centimetres before applying the formula. The result is a body fat percentage estimate.

Male

BF% = 495 / (1.0324 − 0.19077 × log(waist − neck) + 0.15456 × log(height)) − 450

Female

BF% = 495 / (1.29579 − 0.35004 × log(waist + hip − neck) + 0.22100 × log(height)) − 450

Why Body Fat Percentage Matters

Body weight alone is a poor measure of health and fitness because it does not distinguish between muscle and fat. Two people of the same height and weight can have vastly different body compositions — one may be muscular and lean while the other carries excess fat. Body fat percentage corrects for this by measuring the proportion of total weight that is fat tissue.

Tracking body fat over time gives you far more useful feedback than the scale. If you are following a resistance training programme and eating at a slight surplus, your weight may increase while your body fat percentage decreases — a highly positive outcome that the scale would misrepresent as failure.

Retest under the same conditions: same time of day, same hydration level, same tape measure technique. Consistency in measurement method is more important than which method you use.

Frequently asked questions

How does the US Navy body fat method work?
The US Navy circumference method estimates body fat percentage using body measurements rather than skinfold calipers or DEXA scans. For males, it uses neck, waist, and height measurements. For females, it adds a hip measurement. The values are entered into a logarithmic formula developed to approximate body density and then convert that density estimate into a body fat percentage using the Siri equation. It is the standard measurement used by the United States military to assess fitness for service.
How accurate is the Navy body fat calculation?
The Navy method is considered reasonably accurate for most people, with studies showing error margins of around 3 to 5 percentage points compared to gold-standard methods like DEXA scanning. It tends to overestimate body fat in very lean individuals and underestimate it in people who carry fat more centrally. For a quick, cost-free estimate it is highly practical. Use the number as a directional guide and retest under the same conditions to track change over time.
Where should I measure my waist for the Navy method?
For the Navy method, the waist measurement is taken at the level of the navel for males. For females, waist is measured at the narrowest point between the ribs and the hips. It is important to measure at the end of a normal exhale, not while sucking in or pushing out. Always use a flexible fabric tape measure and keep it level and snug but not compressing the skin.
Why do women need a hip measurement?
Women naturally carry a higher proportion of fat in the hip and gluteal region compared to men. The Navy formula for females incorporates the hip circumference to capture this sex-specific fat distribution pattern, which improves accuracy. Without it, the formula would systematically underestimate body fat in women. The hip is measured at the widest point of the buttocks.
What are healthy body fat percentage ranges for men and women?
For men, essential fat is roughly 2 to 5 percent, athletic range is 6 to 13 percent, fitness range is 14 to 17 percent, average is 18 to 24 percent, and above 25 percent is considered obese. For women, essential fat is 10 to 13 percent, athletic is 14 to 20 percent, fitness is 21 to 24 percent, average is 25 to 31 percent, and above 32 percent is considered obese. These are general guidelines and individual health outcomes depend on many other factors.
Can I reduce body fat through diet alone without exercising?
Yes, a caloric deficit through diet alone will reduce body fat, but combining diet with resistance training is significantly more effective. Resistance training preserves and builds lean muscle mass, which raises your resting metabolic rate and improves body composition even at the same body weight. Without exercise, a large portion of weight lost during a caloric deficit will include muscle tissue, which is counterproductive for long-term health and metabolism.

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