Premium Converters
Loading
Loading, please wait.
Loading
Loading
Estimate body fat percentage with the US Navy tape-measure method using neck, waist and hip in cm or inches — a no-cost alternative to DEXA scans for men and women.
Health
Generated on July 8, 2026
Estimate body fat percentage with the US Navy tape-measure method using neck, waist and hip in cm or inches — a no-cost alternative to DEXA scans for men and women.
This body-fat calculator uses the US Navy tape-measure method to estimate body-fat percentage from your height, neck, and waist (plus hip for women). Originally developed in 1984 by Hodgdon and Beckett for the US military's fitness standards, it is a no-cost alternative to expensive DEXA scans or skinfold calipers. With careful measurement under good conditions, accuracy is within roughly ±3% of laboratory methods — more than adequate for tracking trends over time, setting realistic fitness goals, and monitoring body-composition progress during a diet or training cycle.
Formula
Men: BFP = 495 / (1.0324 − 0.19077 × log10(waist − neck) + 0.15456 × log10(height)) − 450. Women: similar with waist + hip − neck. All measurements in centimeters.BMI told you you're 'normal' but you can still pinch a soft layer around your waist and you're wondering what's actually going on. The honest answer is: BMI can't see fat. It sees mass. Two people at the same height and weight can be wildly different — one 18 percent body fat with visible muscle, the other 32 percent body fat with almost none. The US Navy tape-measure method this calculator uses was originally built in 1984 for the American military's fitness standards and lands within plus or minus 3 percent of a DEXA scan when you measure carefully. Carefully matters: neck just below the Adam's apple, waist at its narrowest point above the navel, hip at the widest point around the buttocks. Same time of day, same posture, every measurement. The phrase 'skinny-fat' exists for a reason — a slim-looking person with low muscle and high body fat is still at metabolic risk, and BMI completely misses it. The cleanest target most people should aim for is 14 to 17 percent body fat for men or 21 to 24 percent for women, where you start seeing real muscle definition without going into hormone-disrupting territory. Track monthly, not weekly — daily readings are mostly water noise. And remember: very low body fat is not healthy. Below 5 percent for men or 13 percent for women, the body starts shutting things down — hormones drop, periods stop, recovery slows. Lean is the goal, not skeletal.
This body-fat calculator uses the US Navy tape-measure method to estimate body-fat percentage from your height, neck, and waist (plus hip for women). Originally developed in 1984 by Hodgdon and Beckett for the US military's fitness standards, it is a no-cost alternative to expensive DEXA scans or skinfold calipers. With careful measurement under good conditions, accuracy is within roughly ±3% of laboratory methods — more than adequate for tracking trends over time, setting realistic fitness goals, and monitoring body-composition progress during a diet or training cycle.
The US Navy formula derives body density from specific body-circumference measurements (waist − neck for men; waist + hip − neck for women) using logarithmic functions. Density is then converted into fat percentage via the Siri equation (495/density − 450), which is a standard body-composition conversion. All inputs must be in centimeters for the formula to work correctly; the calculator handles conversion automatically if you enter inches.
American Council on Exercise body-fat percentage ranges for men and women by fitness level.
| Category | Men (%) | Women (%) | Notes |
|---|---|---|---|
| Essential Fat | 2–5 | 10–13 | Minimum for health — hormonal, organ function |
| Athletes | 6–13 | 14–20 | Competitive bodybuilder / elite athlete range |
| Fitness | 14–17 | 21–24 | Visible muscle definition, lean physique |
| Average | 18–24 | 25–31 | Typical healthy adult; no visible muscle definition |
| Obese | 25+ | 32+ | Health risks rise; weight management recommended |
An athletic man at 10% body fat shows clear abdominal separation; a woman at 18% shows similar definition.
Essential-fat minimums (2–5% men / 10–13% women) are biological limits — below these, hormones fail.
Average North American / European adult: ~22% men, ~32% women — up from ~15% / 27% in 1960.
BMI and body fat % can diverge sharply: a muscular man at 80 kg with BMI 26 ('overweight') may actually be 12% body fat ('athletic').
A man at 180 cm with neck 40 cm and waist 85 cm has approximately 15% body fat — the 'Fitness' category for men.
A woman at 165 cm with neck 32 cm, waist 75 cm, and hip 95 cm has about 24% body fat — 'Fitness' for women.
A man at 175 cm with neck 42 cm and waist 100 cm has around 25% body fat — borderline high, 'Average' category.
A male athlete at 185 cm with neck 41 cm and waist 80 cm measures about 10% body fat — the 'Athlete' category.
A woman at 170 cm with neck 33 cm, waist 85 cm, and hip 100 cm has roughly 29% body fat — 'Average' category.
A man at 170 cm with neck 38 cm and waist 78 cm measures around 13% body fat — firmly within the 'Athlete' range, typical of lean recreational athletes.
Jump to a ready-made conversion — useful for quick reference and sharing:
Ideal Weight and Body Frame: Why One Number Isn't the Answer
The formulas give a tidy target, but two people the same height can be healthy at very different weights. Here's what the number means — and what it quietly ignores.
BMI Isn't the Whole Story: Reading Your Body Metrics Properly
BMI is a screening shortcut, not a verdict. Here's how to read it honestly and which numbers to check alongside it.
BMI Calculator
Calculate Body Mass Index against WHO and Asian-population thresholds for men and women using kg or lb, cm or inches, with healthy-range guidance.
BMR Calculator
Estimate Basal Metabolic Rate using the Mifflin-St Jeor equation by sex, age, weight and height — the resting kcal/day baseline for diet planning.
TDEE Calculator
Compute Total Daily Energy Expenditure from BMR and activity multiplier (sedentary to extra active) to set kcal targets for cutting, maintenance, or bulking.
Ideal Weight Calculator
Find your ideal weight range in kg and lb using the Robinson, Miller, Devine and Hamwi formulas alongside the BMI 18.5-24.9 healthy band for men and women.
Water Intake Calculator
Calculate daily water intake in millilitres or litres from body weight and exercise minutes, with hot-climate, pregnancy and breastfeeding adjustments.
Macro Calculator
Calculate your daily protein, carbohydrate, and fat targets based on your goals.
Pregnancy Due Date Calculator
Estimate baby's due date using Naegele's rule (LMP + 280 days), adjusted for cycle length, with conception date, trimester boundaries and current week and day.
Ovulation Calculator
Predict ovulation day and the six-day fertile window from your last menstrual period and cycle length for conception planning and natural family planning.
Browse all Health calculators & converters
See every tool in this category, plus FAQs and category-specific guides.