Body Fat Calculator
The U.S. Navy method estimates body fat percentage from a tape measure: height, neck and waist for men, plus hips for women. A man who is 180 cm tall with a 38 cm neck and 84 cm waist has about 15% body fat. Healthy averages are roughly 14 to 24% for men and 21 to 31% for women.
At the navel for men, narrowest point for women
U.S. Navy circumference method. ACE categories.
How to use the Body Fat Calculator
- Choose male or female.
- Enter your height, then your neck and waist measurements in cm or inches.
- Women also enter hip circumference at the widest point.
- Read your body fat percentage and category, which update as you type.
Formula
Men: 495 ÷ (1.0324 - 0.19077 × log10(waist - neck) + 0.15456 × log10(height)) - 450 · Women: 495 ÷ (1.29579 - 0.35004 × log10(waist + hip - neck) + 0.221 × log10(height)) - 450These are the U.S. Navy circumference equations with all measurements in centimetres. Categories follow the American Council on Exercise (ACE) ranges.
Body fat categories (ACE)
- Essential fat: men 2 to 5%, women 10 to 13%
- Athletes: men 6 to 13%, women 14 to 20%
- Fitness: men 14 to 17%, women 21 to 24%
- Average: men 18 to 24%, women 25 to 31%
- Above average: men 25% and over, women 32% and over
How to measure
- Use a flexible tape, stand relaxed and breathe out normally.
- Neck: just below the larynx (Adam's apple), tape sloping slightly down at the front.
- Waist: men at the navel; women at the narrowest point.
- Hips (women): at the widest point of the buttocks.
- Measure two or three times and use the average.
Accuracy
Tape methods are usually within 3 to 4 percentage points of lab methods such as DEXA. They are best for tracking change over time with the same technique, rather than for a single exact number.
Body Fat Calculator questions
What is a healthy body fat percentage?
For most men, 14 to 24% is in the fitness to average range; for most women it is 21 to 31%. Athletes are often lower (6 to 13% for men, 14 to 20% for women). Essential fat, the minimum for normal body function, is about 2 to 5% for men and 10 to 13% for women.
How accurate is the Navy body fat method?
The U.S. Navy tape method is typically within about 3 to 4 percentage points of DEXA scans for most people. Accuracy depends on careful, consistent measuring. It is less accurate for very lean or very muscular people, whose body shape differs from the reference population.
Which body fat measurement method is most accurate?
DEXA scans and hydrostatic (underwater) weighing are the most accurate, within about 1 to 3%, but need special equipment. At home, the Navy tape method and skinfold calipers in trained hands are reasonable. Bioimpedance scales are convenient but vary with hydration.
How do I measure my neck, waist and hips correctly?
Use a flexible tape snug against the skin without compressing it. Measure the neck just below the Adam's apple, the waist at the navel for men or the narrowest point for women, and the hips at their widest point. Take each measurement twice and average them.
Can I have a normal BMI but high body fat?
Yes. This is sometimes called normal-weight obesity: weight is in the healthy BMI range, but body fat is high because muscle mass is low. Because BMI cannot tell fat from muscle, a body fat estimate gives better insight, especially for inactive people.
Why does my body fat reading change from day to day?
Small changes of 1 to 2 points are normal, caused by bloating, hydration and slight differences in where the tape sits. Measure at the same time of day, ideally in the morning before eating, and compare weekly or monthly averages rather than single readings.
How quickly can I safely reduce body fat?
Losing about 0.5 to 1% of body weight per week is a safe, muscle-sparing pace, which usually means around 1 percentage point of body fat per month. Faster loss tends to include more muscle. Combine a modest calorie deficit with strength training and enough protein.
Should I focus on body fat or body weight?
Body fat is the better guide to health and fitness progress. You can lose fat while gaining muscle, so the scale may barely move while your waist and body fat drop. Track body fat percentage, waist size and strength alongside weight.