Body Fat Calculator
Estimate your body fat from a tape measure using the U.S. Navy method, with your category, fat and lean mass, and a second estimate from BMI.
Use this converter to convert to the unit accepted by the calculator.
Example
Sample: a 25-year-old man, 70 kg, 178 cm, neck 50 cm, waist 96 cm.
This is a sample result, not your calculation. Enter your own values to replace it.
Enter your measurements, then calculate.
Body Fat
The full report
| Body Fat (U.S. Navy Method) | — |
|---|---|
| Body Fat Category | — |
| Body Fat Mass | — |
| Lean Body Mass | — |
| Ideal Body Fat for Given Age (Jackson & Pollock) | — |
| Body Fat to Lose to Reach Ideal | — |
| Body Fat (BMI method) | — |
Circumference estimates, not a body scan. The Navy method reads where fat sits; the BMI method knows only height, weight and age and cannot tell muscle from fat, which is why the two rarely agree. Useful for tracking a direction over months, not for a diagnosis.
Check your measurements
How to use this calculator
- Pick the unit tab that matches your tape and scales. Switching tabs converts what you have already typed rather than clearing it.
- Choose your gender and enter your age — both change which formula and which reference figures apply.
- Enter weight, height, neck and waist. Women are also asked for the hip, because the female formula uses it.
- Press Calculate for your percentage, your category on the scale, and the full report.
How to measure
The result is only as good as the tape. Measure to the nearest quarter inch or half centimetre, standing relaxed, without holding your breath or pulling the tape tight.
- Neck — just below the larynx, sloping slightly downward at the front.
- Waist — at the navel for men; at the narrowest point for women.
- Hip — at the widest point, feet together.
Measure at the same time of day each time. A full stomach can move a waist by a centimetre, which is enough to shift the percentage by half a point.
A worked example
A 25-year-old man weighing 70 kg at 178 cm, with a 50 cm neck and a 96 cm waist, comes out at 15.7% body fat — the Fitness range. That is 11.0 kg of fat against 59.0 kg of lean mass. The typical figure for his age is 10.5%, so he is carrying about 3.6 kg more fat than that reference. The BMI method puts him at 16.1%, half a point higher.
Why two estimates, and why they differ
The Navy method reads circumferences, so it knows something about where fat sits. The BMI method knows only height, weight and age, and cannot tell muscle from fat — which is why a heavily muscled person reads high on it and someone light but untrained reads low. Showing both, and the gap between them, says more than either would alone. A point or two apart is ordinary; a wide gap usually means an unusual amount of muscle.
What the categories mean
| Category | Men | Women |
|---|---|---|
| Essential fat | 2–5% | 10–13% |
| Athletes | 6–13% | 14–20% |
| Fitness | 14–17% | 21–24% |
| Average | 18–24% | 25–31% |
| Obese | 25%+ | 32%+ |
Women's figures are higher throughout, and that is biology rather than fitness: essential reproductive fat has no male equivalent. Comparing a woman's percentage against a man's scale is simply the wrong comparison.
What this cannot tell you
It is an estimate from a tape, typically within a few percentage points of a DEXA scan and least reliable at the extremes. It says nothing about where fat is stored internally, which is what actually drives metabolic risk. Its real value is consistency: measured the same way each month, the direction it moves is far more trustworthy than any single reading. This is general information, not medical advice — talk to a clinician before acting on it.
For related figures see the BMI calculator and the ideal weight calculator.
Read more
- Body Fat Percentage: What's Healthy? Why body fat percentage beats the scale, what a healthy range looks like for men and women, how to measure it at home, and how to lower it sustainably.
- The Complete Guide to Healthy Weight How BMI, body fat, BMR and calories fit together — a practical, no-fads framework for reaching and maintaining a healthy weight, backed by the numbers.
Frequently asked questions
How does the U.S. Navy method work?
It estimates body fat from circumferences rather than weight. For men it uses neck, waist and height; for women it adds the hip. The idea is that where a tape sits tells you more about fat than a scale can, because it distinguishes a thick waist from a heavy frame.
Why do the Navy and BMI figures disagree?
Because they measure different things. The Navy method reads where fat actually sits. The BMI method knows only height, weight and age, so it cannot tell muscle from fat — a muscular person reads high and someone light but soft reads low. A gap of a percentage point or two is normal; a large one usually means an unusual amount of muscle.
How accurate is this?
It is an estimate, typically within about 3–4 percentage points of a DEXA scan for most people, and less reliable at the extremes. Its real strength is consistency: measured the same way each time, it tracks a direction over months far better than it pins down a single number today.
How should I measure?
To the nearest quarter inch or half centimetre, with a flexible tape, standing relaxed and not holding your breath. Neck just below the larynx, sloping slightly downward at the front. Waist at the navel for men, at the narrowest point for women. Hip at the widest point. Measure at the same time of day each time — a full stomach can move the waist by a centimetre.
What is a healthy body fat percentage?
For men, roughly 2–5% is essential fat, 6–13% athletic, 14–17% fitness, 18–24% average and 25%+ obese. For women the figures are higher because of essential reproductive fat: about 10–13% essential, 14–20% athletic, 21–24% fitness, 25–31% average and 32%+ obese. The gauge places your reading on that scale.
What is the ideal figure this shows?
It is Jackson & Pollock's reference value for your age and sex — the percentage typical of a healthy person of those years, not a target you must hit. It rises with age for both sexes, which is normal and expected.
Which unit tab should I use?
Whichever matches your tape and scales. US Units takes pounds and feet with inches; Metric Units takes kilograms and centimetres; Other Units takes stones and pounds, metres, and inches for the girths. Switching tabs converts what you have already typed, so nothing is lost.
Related calculators
- BMI Calculator Calculate your Body Mass Index (BMI) from height and weight, see your WHO weight category, and your healthy weight range.
- BMR Calculator Estimate your Basal Metabolic Rate — the calories you burn at rest.
- Calorie Calculator Find your daily calorie needs for maintaining, losing or gaining weight.
- Ideal Weight Calculator Find a healthy target weight range for your height using established formulas.
- Protein Calculator Estimate daily protein needs based on body weight and activity.
- Fat Intake Calculator Estimate recommended daily fat intake within your calorie target.
About this calculator
Method reviewed for accuracy on July 17, 2026
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