Body composition
Body Fat Percentage Calculator
This free body fat percentage calculator estimates your body fat from a tape measure, using the US Navy method. No calipers, no scale, no gym visit: just a few circumference measurements. It is free, repeatable at home, and reliable for tracking changes over time.
Your estimate
Estimated body fat
Body fat
17%
- Category
- Fitness
- Method
- US Navy
- tape measurements
How this body fat calculator works
The US Navy body fat method estimates body fat from circumference measurements and your height. It is the same formula used by the US armed forces, calibrated in inches (we convert from centimetres for you):
- Men use neck and waist circumference.
- Women use neck, waist and hip circumference: hips are required for the formula to work.
How to measure body fat accurately: use a flexible tape, keep it level and snug (not tight), and measure on bare skin first thing in the morning. Men measure the waist at the navel; women measure the waist at the narrowest point and the hips at the widest. The secret to a useful number is consistency: measure the same way each time.
Body fat percentage categories (ACE classification)
General body composition ranges for men and women. These are broad guides for fitness, not medical targets: health depends on much more than a single number.
| Category | Men | Women |
|---|---|---|
| Essential fat | 2–5% | 10–13% |
| Athletes | 6–13% | 14–20% |
| Fitness | 14–17% | 21–24% |
| Acceptable | 18–24% | 25–31% |
| Obese | 25%+ | 32%+ |
What is an ideal body fat percentage by age?
Body fat tends to creep up with age, so a healthy target shifts over the years. A widely shared fitness chart (popularised by BuiltLean, based on Accu-Measure body fat guidelines) puts a healthy body fat around 8.5% for men and 17.7% for women at age 20, rising to roughly 20.9% and 26.3% by age 55. These are popular fitness reference points, not medical goals, and are not from the Jackson & Pollock research paper.
| Age | Men | Women |
|---|---|---|
| 20 | 8.5% | 17.7% |
| 25 | 10.5% | 18.4% |
| 30 | 12.7% | 19.3% |
| 35 | 13.7% | 21.5% |
| 40 | 15.3% | 22.2% |
| 45 | 16.4% | 22.9% |
| 50 | 18.9% | 25.2% |
| 55 | 20.9% | 26.3% |
Worked examples
- Man, 180 cm, 38 cm neck, 85 cm waist: the formula gives about 16.2% body fat, in the fitness range.
- Woman, 165 cm, 32 cm neck, 75 cm waist, 98 cm hips: about 29.2% body fat.
Knowing your body fat percentage unlocks a more precise calorie estimate: it feeds the Katch-McArdle equation, which is based on lean body mass. Drop the figure into the body recomposition calculator to plan building muscle while losing fat.
Fat mass vs lean mass by body fat percentage
For a fixed bodyweight, your body fat percentage decides how those kilograms split between fat and lean tissue. At the same weight, a lower body fat percentage means more lean mass and less fat.
| Body fat % | Fat mass | Lean mass |
|---|---|---|
| 15% | 12 kg | 68 kg |
| 20% | 16 kg | 64 kg |
| 25% | 20 kg | 60 kg |
| 30% | 24 kg | 56 kg |
Example profile: a person weighing 80 kg; lean mass uses the formula weight × (1 − body fat %).
How does the US Navy body fat method work?
The US Navy method estimates body fat from circumference measurements and your height, using a formula the military adopted because it needs only a tape measure. Men provide neck and waist; women add hips, because the female formula relies on all three.
Behind the scenes it compares the size of your waist (where most stored fat sits) against your neck and height, then converts that relationship into a percentage. It does not measure fat directly, but it correlates well enough to be useful, especially for tracking your own trend.
BMI vs body fat percentage: what's the difference?
BMI compares your weight to your height, while body fat percentage estimates how much of your body is actually fat. BMI cannot tell muscle from fat, so a lean, muscular person can read as overweight on BMI despite carrying little fat.
Body fat percentage answers the question BMI cannot: how is your weight made up. The two are complementary, but for composition goals the percentage is the more informative number.
What is a healthy body fat percentage?
As a broad guide, a fitness-level body fat is around 14 to 17% for men and 21 to 24% for women, with average ranges sitting a little higher. The detailed bands for essential fat, athletes, fitness, average and above-average are in the body fat percentage categories table earlier on this page.
Treat those ranges as broad fitness guides, not medical targets. Health depends on far more than one number, including where fat is stored, your activity and your blood markers.
What are the ways to measure body fat (and their limits)?
- Tape measure (US Navy): free and repeatable at home, but sensitive to how you measure, so consistency matters most.
- Skinfold calipers: cheap and reasonably accurate in trained hands, yet easy to get wrong without practice.
- Bioelectrical impedance (smart scales): instant but swayed by hydration, food and time of day.
- DEXA scan and hydrostatic weighing: the most accurate, but they cost money and require a clinic visit.
No home method is perfect, so the smartest use is tracking the trend with one consistent method rather than chasing a single exact figure. Once you have a number, your body fat percentage feeds a more precise TDEE via Katch-McArdle: see the TDEE calculator.
Good to know
Frequently asked questions
How does the US Navy body fat method work?
It estimates body fat from tape-measure circumferences (neck and waist for men, plus hips for women) together with your height. It is free, repeatable at home, and reasonably accurate for tracking changes over time.
How accurate is the Navy body fat calculator?
For most people it lands within a few percentage points of more expensive methods like DEXA. Its real strength is consistency: measure the same way each time and it reliably shows whether your body fat is trending down.
How should I take the measurements?
Use a flexible tape, keep it level and snug (not tight), and measure on bare skin first thing in the morning. Men measure the waist at the navel; women measure at the narrowest point and the hips at the widest point.
What is a healthy body fat percentage?
A common fitness range is roughly 14–24% for men and 21–31% for women, spanning the fitness and average bands in the categories table on this page, with athletes often lower. These are broad guides, not medical targets. Health depends on much more than a single number.
What body fat percentage do you need to see abs?
Visible abs usually start to show around 10–12% body fat for men and 18–20% for women, though genetics and where you store fat shift this. Everyone has abdominal muscles: they only become visible once the layer of fat over them is thin enough. Use this calculator to track whether that layer is trending down.
Is BMI or body fat percentage more accurate?
For body composition, body fat percentage is more informative, because BMI only compares weight to height and cannot tell muscle from fat. A muscular person can have a high BMI yet low body fat. BMI is a quick population screen, while body fat % better reflects what your body is actually made of.
How do you lower your body fat percentage?
Lower body fat by eating in a modest calorie deficit, keeping protein high (about 1.6–2.2 g per kg), and doing resistance training to keep muscle while the fat comes off. As fat drops and muscle stays, your body fat percentage falls. Our calorie deficit and macro calculators can set the targets to do this.
Is this medical advice?
No. This is general information and education only, not medical or nutritional advice. Consult a professional for any health or body-composition concerns.
Evidence
Sources & references
- Hodgdon JA, Beckett MB (1984). Prediction of percent body fat from circumferences and height. · Naval Health Research Center: the original US Navy body fat method.
- American Council on Exercise (ACE): Body fat percentage norms · Reference ranges used for the category table above.
- Jackson AS, Pollock ML (1978). Generalized equations for predicting body density. · The underlying body density and body fat equations. This paper provides the method, not the age chart itself.
- Body fat percentage by age chart (Accu-Measure / AccuFitness, popularised by BuiltLean) · Source of the age-based reference points shown above. A popular fitness chart, not from the Jackson & Pollock paper and not a medical standard.
- Examine.com: Body composition · Independent, research-based nutrition reference.
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