Body Fat Percentage Calculator
Estimate body fat % from tape measurements using the US Navy method. See your category, fat mass, and lean mass — no calipers or gym required.
Added May 17, 2026
Input
Measure at the navel (narrowest point for women).
Measure just below the larynx, sloping slightly downward.
Used to calculate fat mass and lean mass in kg.
Result
Enter a value for biological sex to see your result.
How it works
Estimates body fat percentage using the U.S. Navy circumference method — no calipers or DEXA scan needed. Just a tape measure and a few body measurements give you fat %, category, and optionally fat and lean mass.
Formula
Male: %BF = 495 / (1.0324 − 0.19077 × log₁₀(waist − neck) + 0.15456 × log₁₀(height)) − 450 Female: %BF = 495 / (1.29579 − 0.35004 × log₁₀(waist + hip − neck) + 0.22100 × log₁₀(height)) − 450
- waist
- Waist circumference in cm (measured at navel)
- neck
- Neck circumference in cm (just below larynx)
- hip
- Hip circumference in cm at widest point (females only)
- height
- Height in cm
Step by step
- 01Convert all measurements to centimetres if using imperial units.
- 02For males: subtract neck from waist; take log₁₀ of the result and of height.
- 03For females: add waist and hip, subtract neck; take log₁₀ of the result and of height.
- 04Plug the logged values into the Navy formula to get body fat %.
- 05If weight is entered, multiply body fat % by weight to get fat mass; lean mass = weight − fat mass.
- 06Look up the body fat % in the ACE category table (Essential / Athletes / Fitness / Average / Obese).
Examples
Male · 175 cm · waist 85 cm · neck 38 cm · 75 kg
log₁₀(85 − 38) = log₁₀(47) ≈ 1.672; log₁₀(175) ≈ 2.243. Denominator ≈ 1.060 → 495/1.060 − 450 ≈ 17.0% (Fitness category).
Inputs
- Biological sex:
- male
- Unit system:
- metric
- Height:
- 175
- Waist circumference:
- 85
- Neck circumference:
- 38
- Body weight (optional):
- 75
Result
- Body fat %:
- 17.0%
- Category:
- Fitness
Female · 165 cm · waist 75 cm · neck 33 cm · hip 98 cm · 65 kg
log₁₀(75 + 98 − 33) = log₁₀(140) ≈ 2.146; log₁₀(165) ≈ 2.217. Denominator ≈ 1.035 → 495/1.035 − 450 ≈ 28.5% (Average category).
Inputs
- Biological sex:
- female
- Unit system:
- metric
- Height:
- 165
- Waist circumference:
- 75
- Neck circumference:
- 33
- Hip circumference:
- 98
- Body weight (optional):
- 65
Result
- Body fat %:
- 28.5%
- Category:
- Average
Frequently asked questions
How accurate is the US Navy body fat method?
The Navy method is accurate to within roughly ±3–4 percentage points of DEXA (gold-standard) scanning for most adults. It is more accurate than BMI for assessing body composition but less accurate than hydrostatic weighing or DEXA. Measurement consistency matters more than single-reading precision.
Where exactly do I measure my waist, neck, and hip?
Waist: measure horizontally at the navel for men; at the narrowest point for women. Neck: just below the larynx (Adam's apple), tapering slightly downward — do not suck in. Hip (women only): the widest point around the buttocks. Use a flexible, non-stretch tape and keep it level.
What are healthy body fat percentage ranges?
ACE (American Council on Exercise) categories: Men — Essential fat 2–5%, Athletes 6–13%, Fitness 14–17%, Average 18–24%, Obese ≥25%. Women — Essential fat 10–13%, Athletes 14–20%, Fitness 21–24%, Average 25–31%, Obese ≥32%.
Why does this use the Navy method instead of BMI?
BMI uses only height and weight, so it cannot distinguish muscle from fat — a muscular athlete and an out-of-shape person can have identical BMI. The Navy method uses circumference measurements that correlate with fat distribution, giving a more meaningful body-composition estimate.
Can I use this calculator for teens or children?
The Navy formula was developed and validated for adults aged 18+. For adolescents, different reference norms apply. Consult a paediatrician or use age-specific standards.