Body fat calculator

How this body fat calculator works

It uses the US Navy method, which estimates body fat from height and a few tape measurements: neck and waist for men, neck, waist and hips for women. It was developed to assess service members quickly without equipment, and studies put it within about 3–4 percentage points of a DEXA scan for most people. That is plenty for tracking whether you are heading the right way.

How to measure properly

Use a soft tape, first thing in the morning before eating. Neck: just under the Adam's apple, tape sloping slightly down at the front. Waist for men: level with the navel, relaxed, not sucked in. Waist for women: at the narrowest point, usually just above the navel. Hips: around the widest part of the buttocks. Do not pull the tape tight - it should sit flat on the skin without denting it.

What the categories mean

For men, roughly: under 6% essential fat only (not sustainable), 6–13% athletic, 14–17% fit, 18–24% average, 25%+ above average. For women everything sits about 8 points higher because of essential fat: 14–20% athletic, 21–24% fit, 25–31% average, 32%+ above average. "Average" is not a problem; it is where most people are. The waist-to-height ratio next to it is the number the NHS uses for health risk - under 0.5 is the target.

Why this beats the scales

Two people can weigh the same and look completely different. Body fat percentage - and better still, the fat mass and lean mass numbers above - tells you what your weight is made of. Re-measure every 3–4 weeks. If lean mass holds and fat mass falls, the plan is working even on weeks the scales sulk. Not sure whether to cut or build first? The fat loss vs muscle guide answers that.

FAQs

What is a healthy body fat percentage?

For men roughly 10–20% and for women 20–30% covers the fit-to-average range. Athletes sit lower; above 25% for men or 32% for women is where health risk starts to rise. Women naturally carry more essential fat, so the ranges are not comparable across sexes.

How accurate is the tape measure (US Navy) method?

Typically within 3–4% of a DEXA scan for most body types, which is similar to or better than most bathroom-scale bioimpedance readings. It is less accurate for very muscular or very lean people. Its real value is consistency - measure the same way each time and the trend is reliable.

Is body fat percentage better than BMI?

For anyone who trains, yes. BMI cannot tell muscle from fat; body fat percentage can. BMI is still useful as a quick population screen, and waist-to-height ratio is a good middle ground that only needs a tape.

How fast can I lose body fat?

Around 0.5 kg of fat a week is realistic and sustainable - roughly 0.5 percentage points a week for an 80–90 kg person. Faster than that usually means losing muscle too.