Body Fat Calculator

Free body fat percentage calculator

This body fat calculator estimates your body fat percentage using the U.S. Navy circumference method— a formula that needs only a tape measure and a few measurements. It's a practical way to track body composition at home, where scales and BMI fall short.

Why body fat beats the bathroom scale

Weight alone can't tell muscle from fat, and neither can BMI. Two people at the same height and weight can have very different body compositions. Estimating body fat percentage splits your weight into fat mass and lean mass, which is what actually matters for fitness and health goals.

Measure well for the best estimate

Accuracy depends on good measurements: keep the tape snug but not tight, level around the body, and measure the neck below the larynx and the waist at the navel (men) or narrowest point (women). Track the same way each time and the trend will be reliable even if any single reading is a little off. Everything is calculated privately in your browser — this is an estimate, not medical advice.

Body fat percentage explained (U.S. Navy method)

The scale tells you how much you weigh, but not what that weight is made of. Body fat percentage does — and it's a far better gauge of fitness than weight or BMI alone. Here's what it means, what's healthy, and how to estimate it at home.

What it actually measures

Body fat percentage is simply the share of your total body weight that is fat, versus lean mass (muscle, bone, organs, water). Someone at 80 kg with 15% body fat carries 12 kg of fat and 68 kg of lean mass. Two people at the same weight can look and perform completely differently depending on this split.

Why it beats BMI

BMI uses only height and weight, so it can't tell muscle from fat. A muscular athlete often lands in the “overweight” BMI band despite being lean, while someone with low muscle can have a “normal” BMI yet high body fat. Body fat percentage sidesteps that by measuring composition directly. See what BMI is for the contrast.

Healthy ranges

Rough guidelines (they vary by source and age):

• Men: essential 2–5%, athletes 6–13%, fitness 14–17%, average 18–24%, high 25%+.
• Women: essential 10–13%, athletes 14–20%, fitness 21–24%, average 25–31%, high 32%+.

Women naturally carry more essential fat for hormonal and reproductive health — comparing across sexes on the same scale is a mistake.

How the U.S. Navy method works

Precise methods like DEXA scans and hydrostatic weighing are accurate but expensive. The U.S. Navy circumference method gets impressively close using only a tape measure. It feeds a few measurements — height, neck and waist (plus hips for women) — into a validated formula. For most people it lands within about 3–4% of a lab measurement.

Measure well

Accuracy lives and dies by the tape:

• Measure the neck just below the larynx, tape sloping slightly down at the front.
• Measure the waist at the navel for men, at the narrowest point for women.
• Measure the hips (women) at the widest point.
• Keep the tape snug and level, and don't suck in or hold your breath.

Take each measurement a couple of times and average them.

Track the trend, not the single number

Any estimate has error, so don't obsess over one reading. Measure the same way, same time of day, every couple of weeks — the direction is what tells you whether your training and nutrition are working.

Next steps

Pair this with the BMI calculator and the calorie calculator to plan changes. This is educational information, not medical advice.