What is body fat percentage?
Body fat percentage is the share of your total weight that is fat. The rest is lean mass — muscle, bone, organs and water. Unlike BMI, which only compares weight with height, body fat percentage tells you what your weight is made of. Two people can weigh exactly the same and have very different health risks because one carries much more fat, especially around the waist.
Some fat is essential: it protects organs, stores energy, keeps you warm and produces hormones. Women naturally need more body fat than men for healthy hormones, periods and fertility.
How the body fat calculator works (U.S. Navy method)
This body fat calculator uses the U.S. Navy circumference formula developed by Hodgdon and Beckett. It uses tape measurements because fat around the waist and hips grows faster than the neck. In metric units (cm):
- Men: Body fat % = 495 ÷ (1.0324 − 0.19077 × log₁₀(waist − neck) + 0.15456 × log₁₀(height)) − 450
- Women: Body fat % = 495 ÷ (1.29579 − 0.35004 × log₁₀(waist + hip − neck) + 0.22100 × log₁₀(height)) − 450
How to measure correctly
- Measure on bare skin in the morning, standing relaxed. Do not pull the tape tight.
- Neck: just below the larynx (Adam’s apple), tape sloping slightly down at the front.
- Waist: men at the level of the navel; women at the narrowest point of the waist.
- Hips (women): around the widest part of the buttocks.
- Take each measurement twice and use the average.
Studies show the Navy method is usually within about 3–4 percentage points of laboratory tests such as DEXA scans.
Body fat percentage chart for women and men
These categories from the American Council on Exercise (ACE) are widely used:
| Category | Women | Men | Level |
|---|---|---|---|
| Essential fat | 10 – 13% | 2 – 5% | Low |
| Athletes | 14 – 20% | 6 – 13% | Healthy |
| Fitness | 21 – 24% | 14 – 17% | Healthy |
| Average | 25 – 31% | 18 – 24% | Acceptable / rising risk |
| Obese | 32% and above | 25% and above | High |
Body fat tends to increase slightly with age, so a few extra percent may be acceptable after 50.
Benefits of knowing your body fat percentage
- More meaningful than weight alone: you can see fat loss even when the scale barely moves because you are gaining muscle.
- Better health risk picture: high body fat, especially belly fat, is linked with insulin resistance, high blood pressure and fatty liver.
- Smarter goals: aim to lose fat while keeping muscle, rather than chasing a number on the scale.
- More accurate calorie needs: enter your result in the TDEE calculator to use the Katch-McArdle formula.
Health warnings
- This is an estimate. Results can be less accurate for very muscular people, older adults, and people with very high body fat.
- Very low body fat (below about 14% in women or 6% in men) can cause missed periods, low testosterone, poor immunity and bone loss.
- Not suitable during pregnancy or for children and teenagers.
- Avoid crash dieting to lower body fat quickly — it mainly removes muscle and water.
How to lower body fat healthily
Combine a modest calorie deficit from the calorie calculator with 2–3 strength sessions a week and enough protein (protein calculator). Choose high-fibre foods, cut back on sugary drinks and refined snacks, and sleep 7–9 hours. Read more in our guide to abdominal fat.
Frequently asked questions
What is a healthy body fat percentage?
For women, about 21–31% is generally healthy, with 21–24% considered fit. For men, about 14–24% is healthy, with 14–17% considered fit. Athletes are often lower.
How accurate is the Navy body fat calculator?
The U.S. Navy method is usually within about 3–4 percentage points of a DEXA scan for most adults, as long as you measure carefully. It is a good, free way to track changes over time.
Why do women have more body fat than men?
Women need more essential fat for hormone production, periods, pregnancy and breastfeeding. That is why healthy ranges for women are about 8–10 percentage points higher than for men.
Can I have a normal BMI but high body fat?
Yes. This is sometimes called “normal-weight obesity”. People with low muscle mass can have a healthy BMI but high body fat, which still raises the risk of diabetes and heart disease.
How often should I measure my body fat?
Every 4 weeks is enough. Measure at the same time of day under the same conditions so you can compare results fairly.
Sources
- Hodgdon JA, Beckett MB. Prediction of percent body fat for U.S. Navy men and women from body circumferences and height. Naval Health Research Center, 1984.
- American Council on Exercise (ACE). Percent body fat norms.
- Okorodudu DO, et al. Diagnostic performance of BMI to identify obesity as defined by body adiposity. Int J Obes 2010.