Choose a calculation method
Deurenberg formula (1991): estimates from height, weight, age, and sex
Back-calculate the target body weight needed to reach your goal body fat %
How to Use the Body Fat Calculator
Body fat percentage is the share of your body weight that is fat. Two people at the same weight can look very different and carry different health risks, so it reveals the “inside” of your body that BMI cannot. This tool estimates body fat using methods such as the BMI method and the U.S. Navy (tape-measure) method.
How to use this tool
Enter your height, weight and age; for the Navy method, also measure your neck and waist (and hips for women) with a tape and enter them. Adding tape measurements improves accuracy. Alongside body fat, the result shows your lean body mass and a target-weight guide.
What the numbers mean
Roughly, 10-19% for men and 20-29% for women is considered average, with athletes typically lower. However, women need a certain amount of body fat for healthy hormonal function, so aiming for extremely low numbers can harm your health. Target a healthy range.
Tips
Body fat readings swing daily with hydration and conditions. Rather than reacting to every reading, measure about once a week at the same time and conditions and judge by the multi-week trend. Plan your cut alongside the TDEE calculator.
How methods compare on accuracy
Body fat can be measured several ways, and accuracy trades off against convenience. Research standards are DXA and hydrostatic weighing, accurate to roughly ±1–2%. Consumer bioelectrical impedance scales are convenient but carry ±3–5% error and are strongly affected by hydration. The circumference (Navy) method used here needs only a tape measure, at roughly ±3–4%.
Why the same scale gives different readings
Impedance devices pass a small current through the body and infer composition from resistance. Water conducts well, so any change in hydration changes the reading. After eating, bathing or training, fluid distribution shifts and the number can move by several per cent. Measure under consistent conditions — on waking, after using the bathroom, before eating or drinking — and read the one- to two-week trend rather than any single day.
Typical ranges
Broadly, 10–20% for adult men and 20–30% for adult women are considered normal. Women carry more essential fat for reproductive function, so the healthy floor is higher (about 3–5% for men, 10–13% for women). Pushing to competitive extremes risks hormonal and menstrual disruption in women, and impaired performance and immune function in both sexes.
Glossary & FAQ
What is body fat percentage?+
Formula:
Body Fat % = (Fat Mass / Body Weight) × 100Example: 70 kg body weight, 14 kg fat mass →
14 / 70 × 100 = 20%It is evaluated alongside lean body mass (LBM) — muscle, bone, and water — to assess overall body composition.
What is the difference between the BMI method and the Navy method?+
The US Navy Method requires waist and neck measurements (and hip for women). It takes more effort but produces results closer to actual body fat, approaching the accuracy of body composition scales.
What is a healthy body fat percentage?+
Men: Essential fat 2–5% / Athlete 6–13% / Fitness 14–17% / Average 18–24% / Obese 25%+
Women: Essential fat 10–13% / Athlete 14–20% / Fitness 21–24% / Average 25–31% / Obese 32%+
Falling below essential fat levels poses serious health risks. Aim for a range appropriate to your goal and lifestyle.
Can strength training lower body fat percentage?+
Combining resistance training with a calorie deficit (see the TDEE calculator) is the most effective approach. During a bulk phase, body fat may temporarily rise, but proper calorie management allows you to gain lean mass while controlling fat gain.
How often should I measure body fat?+
Recommended approach: Measure once or twice per week under consistent conditions (morning, after using the bathroom, before eating), then evaluate the 2–4 week average trend.
・ Deurenberg P, Weststrate JA, Seidell JC. Body mass index as a measure of body fatness. Br J Nutr. 1991;65(2):105-114.
・ Hodgdon JA, Beckett MB. Prediction of percent body fat for U.S. Navy men (Report 84-11) / women (Report 84-29) from body circumferences and height. Naval Health Research Center; 1984.
・ American Council on Exercise (ACE). Percent Body Fat Norms for Men and Women. 2009.
・ Taylor KM, Castellani MP, Bartlett PM, Oliver TE, McClung HL (2024). Development and cross-validation of a circumference-based predictive equation to estimate body fat in an active population. Obesity Science & Practice 10(2):e747. (A recent study in 1904 active adults that rebuilt and cross-validated circumference-based equations against DXA, confirming that circumference methods are convenient but carry error versus DXA, so estimates from formulas like this tool's remain approximations.)
Results are estimates based on population-level equations. Actual body fat percentage may differ from values measured by a body composition scale (e.g., InBody) or DEXA scan. For a detailed health assessment, please consult a physician or registered dietitian. This tool is for informational purposes only and does not constitute medical or nutritional advice.
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