Body Fat Percentage Calculator
Calculate your body fat percentage using the US Navy method or a BMI-based estimate. See your fat mass, lean mass, and where you fall in the body fat categories.
More accurate — requires waist, neck (and hip for women) measurements.
Measure at navel level
Below larynx, sloping down
US Navy Method vs BMI-Based Estimate
US Navy Method
Requires waist, neck, and height measurements (+ hip for women). Accuracy: ±3–5% vs DEXA. Best for regular self-tracking. Developed by Hodgdon and Beckett for the US military in 1984.
BMI-Based Estimate
Requires only weight, height, age, and sex. Lower accuracy (±5–8%) but useful when measurements aren't available. Based on the Deurenberg formula (1991).
DEXA Scan (gold standard)
X-ray based scan measuring bone, fat, and lean mass with ±1–2% accuracy. Requires a clinic visit and costs $50–150. Use for baseline measurements when you need maximum accuracy.
Hydrostatic Weighing
Underwater weighing. Very accurate (±1–3%) but impractical for regular use. Available at some university labs and sports performance centres.
Frequently Asked Questions
How is body fat percentage calculated?
This calculator uses two methods. The US Navy method uses waist, neck, and height measurements (plus hip for women) with a logarithmic formula developed by Hodgdon and Beckett (1984). It is more accurate than BMI-based estimates. The BMI-based method (Deurenberg formula) uses weight, height, age, and sex — less accurate but requires no additional measurements.
What is a healthy body fat percentage?
The American Council on Exercise (ACE) classifies body fat for men as: Essential (2–5%), Athletes (6–13%), Fitness (14–17%), Average (18–24%), Obese (25%+). For women: Essential (10–13%), Athletes (14–20%), Fitness (21–24%), Average (25–31%), Obese (32%+). 'Healthy' depends on your goals — the fitness range is generally associated with good health outcomes.
How accurate is the Navy method?
The US Navy method has an error range of ±3–5% compared to DEXA scans (the gold standard). It is more accurate than BMI-based methods but less accurate than hydrostatic weighing or DEXA. It is the most practical method for self-assessment without equipment. For best accuracy, measure each site twice and average the results.
Where should I measure my waist for the Navy formula?
Men: measure at the level of the navel (belly button), keeping the tape horizontal. Women: measure at the narrowest point of the abdomen (usually just above the navel). Always measure on bare skin, relaxed (not sucked in), at the end of a normal breath.
How is body fat percentage different from BMI?
BMI (Body Mass Index) measures weight relative to height — it cannot distinguish between muscle and fat. Body fat percentage directly measures the proportion of fat tissue in the body. A muscular person can have a high BMI but low body fat (false positive for obesity). BMI is a useful population screening tool but is less useful for individuals with high muscle mass.