What is a healthy body fat percentage?

Using ACE ranges, about 14–24% for men and 21–31% for women covers the fitness and average bands. Essential fat is 2–5% for men and 10–13% for women.

Where do I measure my waist?

Men at the navel; women at the narrowest part of the waist. Keep the tape level and measure after breathing out.

Why do women need a hip measurement?

Women typically store more fat around the hips, so the female equation uses waist + hip − neck.

Is body fat better than BMI?

It describes composition, which BMI cannot. But BMI is simpler and better studied for population health risk; use both.

Do I need to enter my weight?

No. Weight is only used to convert the percentage into kilograms of fat and lean mass.

Health · Free tool

Body Fat Calculator

Estimate body fat percentage with a tape measure — the U.S. Navy circumference method.

BMI tells you how heavy you are for your height, but not what that weight is made of. Two people with the same BMI can carry very different amounts of fat. Body fat percentage looks at composition directly, which is why it is useful for people who train, for tracking progress during weight loss, and for anyone whose BMI seems out of line with how they look.

This calculator uses the U.S. Navy circumference method, developed by Hodgdon and Beckett for military fitness screening. It needs only a tape measure: height, neck and waist for men, plus hips for women. Field studies comparing it with laboratory methods find it is usually within a few percentage points for most adults — less precise than a DEXA scan, but far cheaper and repeatable at home.

Results are grouped using the American Council on Exercise ranges. Add your weight to see how many kilograms are fat and how many are lean mass.

By DailyCalc Editorial Team · Updated 2026-10-03 · 6-min read · 3 sources cited

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U.S. Navy body fat formula (metric)

Men: %BF = 495 ÷ (1.0324 − 0.19077·log₁₀(waist − neck) + 0.15456·log₁₀(height)) − 450; Women: %BF = 495 ÷ (1.29579 − 0.35004·log₁₀(waist + hip − neck) + 0.22100·log₁₀(height)) − 450

The equations estimate body density from circumferences, and 495 ÷ density − 450 (the Siri equation) converts density to body fat percentage. All measurements are in centimetres. Fat mass = weight × %BF ÷ 100, and lean mass is the rest.

waist: Men: horizontally at the navel. Women: at the narrowest point.
neck: Just below the larynx, tape sloping slightly down to the front.
hip: Women only: at the widest point of the buttocks.
height: Standing height without shoes.

Worked example: man, 180 cm, neck 38 cm, waist 85 cm, 80 kg

Measurements taken in the morning, each repeated three times and averaged:

waist − neck = 85 − 38 = 47; log₁₀(47) ≈ 1.6721; log₁₀(180) ≈ 2.2553.
Denominator = 1.0324 − 0.19077 × 1.6721 + 0.15456 × 2.2553 ≈ 1.0619.
%BF = 495 ÷ 1.0619 − 450 ≈ 16.1%.
Category for men: 14–17% is "Fitness".
Fat mass = 80 × 0.161 ≈ 12.9 kg; lean mass ≈ 67.1 kg.

Result: About 16.1% body fat (Fitness range) — roughly 12.9 kg fat and 67.1 kg lean mass.

How to use this body fat calculator

Accurate measuring matters more than anything else.

Step 1: Choose sex

Men need neck and waist; women also need hips.

Step 2: Measure with a flexible tape

Snug but not compressing the skin, after a normal breath out, standing relaxed. Measure each site three times and use the average.

Step 3: Enter measurements in cm

Height, neck, waist (and hip). Weight is optional and only adds fat and lean mass in kilograms.

Step 4: Track the trend

Re-measure every 2–4 weeks under the same conditions; the change matters more than any single reading.

When body fat beats BMI

Situations where composition tells you more than weight:

Strength training

Muscle gain can raise BMI while body fat falls. Tracking %BF shows real progress.

Weight loss

Check that most of the weight lost is fat rather than muscle.

When BMI is ambiguous

A heavily built man at 175 cm with a 102 cm waist and 40 cm neck estimates at about 27.3% — the waist shows the extra weight is mostly fat, something BMI alone cannot separate from muscle.

Fitness standards

Military and some services use the tape method for body composition screening.

Women's tracking

A woman at 165 cm with neck 32, waist 72 and hip 98 cm estimates at about 27.4% — the "Average" band.

Pro tips

Get consistent readings:

Measure first thing in the morning, before eating, for the most repeatable results.
Keep the tape horizontal for waist and hip; use a mirror or ask someone to help.
Do not suck in your stomach — measure after a normal exhale.
Pair %BF with waist-to-height ratio for a fuller picture of central fat.
Compare readings from the same method only; DEXA, smart scales and calipers each give different numbers.

Common mistakes

Why tape estimates sometimes look wrong:

Measuring the waist in the wrong place

Men measure at the navel, women at the narrowest point. A few centimetres off shifts the result by several percent.

Pulling the tape too tight

Compressing skin lowers circumferences and underestimates fat.

Expecting lab precision

Expect an error of around 3–4 percentage points. Use it for trends, not for exact numbers.

Using it in special cases

Pregnancy, very high body fat, and some body shapes reduce accuracy; ask a clinician for a proper assessment.

Sources & references

The formula, thresholds and guidance on this page were checked against these primary sources. Written and reviewed by DailyCalc Editorial Team; last updated 2026-10-03. Spotted an error? Tell us.

Disclaimer: Educational estimate only — not a medical assessment. Tape-measure methods have a margin of error. Speak to a clinician about your health and body composition.

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