Body Fat Calculator
Estimate your body fat percentage using the US Navy tape method. Enter height, neck, and waist measurements for an instant result.
Body Fat Calculator
Measure waist at navel level. Measure neck just below the larynx.
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The body fat calculator estimates your body fat percentage using the US Navy circumference method — a simple tape-measure technique requiring only neck, waist, and hip measurements alongside your height. Body fat percentage is a more informative health metric than weight or BMI alone because it distinguishes fat mass from lean mass (muscle, bone, organs, water). Two people can have identical BMI but very different body compositions — a muscular athlete and an untrained person may weigh the same while having body fat percentages of 12% and 28% respectively. The Navy method is one of the most practical body fat estimation techniques outside a lab setting. It is accurate to within ±3–4% of DEXA scan measurements for most people and requires no equipment beyond a cloth tape measure.
How to Use the Body Fat Calculator
The Body Fat Calculator is designed to give you an accurate answer in seconds. Follow these steps:
- Step 1: Select your sex (male or female) — the Navy formula uses different measurements and constants for each.
- Step 2: Choose metric (cm/kg) or imperial (inches/lbs) and enter your body weight and height.
- Step 3: Measure and enter your neck circumference — measure just below the larynx (Adam's apple), keeping the tape horizontal.
- Step 4: Measure and enter your waist circumference at navel level, keeping the tape snug but not compressing the skin.
- Step 5: Females only — measure hip circumference at the widest point. Click Calculate to see your body fat percentage and category.
No account or sign-up required. All calculations run locally in your browser — nothing is stored or transmitted to any server.
How It Works
Male: %BF = 86.010 × log₁₀(waist − neck) − 70.041 × log₁₀(height) + 36.76 Female: %BF = 163.205 × log₁₀(waist + hip − neck) − 97.684 × log₁₀(height) − 78.387 (All measurements in inches)
The US Navy method was developed by Hodgdon and Beckett and validated against hydrostatic weighing. It uses body circumference measurements as a proxy for subcutaneous fat distribution. For males, only waist and neck circumference are needed — the formula finds the log-difference between them and scales by height. For females, hip circumference is added because women carry more subcutaneous fat in the hip/gluteal region, which the male formula would miss. The output is grouped into standard body fat categories: essential fat (minimum for physiological function), athlete, fitness, average, and high. These ranges differ between males and females because women naturally carry more essential fat for hormonal and reproductive function. Limitations: the Navy method tends to overestimate body fat in very lean individuals and underestimate it in very obese individuals. DEXA scanning remains the gold standard for clinical accuracy.
Frequently Asked Questions
What is a healthy body fat percentage?
For men, 14–17% is considered fitness range and 18–24% is average. For women, 21–24% is fitness range and 25–31% is average. Athletes typically range 6–13% (men) and 14–20% (women). Essential fat — the minimum required for survival — is roughly 2–5% for men and 10–13% for women.
How accurate is the Navy body fat method?
The US Navy method is accurate to within ±3–4% of DEXA scan results for most people in the average body fat range. It is less accurate at the extremes — very lean individuals (below 10% for men) tend to have body fat overestimated, while very obese individuals may be underestimated. For clinical decisions, use DEXA or hydrostatic weighing.
Where exactly do I measure my waist?
Measure your waist at navel level (the belly button), not at the narrowest point. Keep the tape horizontal and parallel to the floor. Take the measurement at the end of a normal exhale with the stomach relaxed — do not suck in. For consistency, measure at the same time of day each time (morning, before eating, is standard).
Why is hip measurement needed for women?
Women naturally store more subcutaneous fat in the hip and gluteal area due to hormonal differences. The male formula uses only waist and neck, which would miss this fat distribution and systematically underestimate body fat in women. The female formula adds hip circumference to account for this difference.
Is the body fat calculator free?
Yes — free with no sign-up required. All calculations run in your browser and no data is stored. Use it alongside the BMI calculator and ideal weight calculator for a fuller picture of your body composition.