Body Fat Percentage Calculator
Get an instant, personalised body fat percentage using the U.S. Navy tape-measurement method — or a quick BMI-based estimate if you don't have a tape measure handy. Free, private, and works on any device.
Body Fat Percentage Chart
Category ranges from the American Council on Exercise (ACE), used to colour your result above.
| Category | Women | Men |
|---|---|---|
| Essential fat | 10 – 13% | 2 – 5% |
| Athletes | 14 – 20% | 6 – 13% |
| Fitness | 21 – 24% | 14 – 17% |
| Acceptable | 25 – 31% | 18 – 24% |
| Obese | 32%+ | 25%+ |
How the Navy Method Works
The circumference-based formula the U.S. Navy has used since the 1980s to estimate body fat for fitness assessments.
What Is Body Fat Percentage?
Body fat percentage is the proportion of your total body weight that is made up of fat, with the remainder being lean mass — muscle, bone, organs and water. Unlike BMI, which only compares your weight to your height, body fat percentage tells you what your weight is actually made of, which is why it's often considered a more meaningful measure of body composition and overall fitness.
This calculator gives you two ways to estimate it. The first is the U.S. Navy tape-measurement method, developed in the 1980s as a fast, no-equipment way for the Navy to assess fitness across large groups of personnel. It uses simple circumference measurements and a logarithmic formula, and remains one of the most accurate at-home methods available, typically within 3–4% of a DEXA scan. The second is a quick BMI-based estimate using the Deurenberg formula, useful when you don't have a tape measure but still want a rough number to work with.
The Navy Method Formula
For men, the formula uses waist and neck circumference along with height:
%BF = 86.010 × log₁₀(waist − neck) − 70.041 × log₁₀(height) + 36.76
For women, hip circumference is added, since fat distribution patterns differ:
%BF = 163.205 × log₁₀(waist + hip − neck) − 97.684 × log₁₀(height) − 78.387
All measurements in this formula are used in inches; if you select metric units, the calculator converts your centimetre measurements automatically before running the calculation.
How to Measure Yourself Correctly
- Neck: Wrap the tape just below your larynx (Adam's apple), angled slightly downward toward the front.
- Waist: Measure at the narrowest point of your torso, usually level with your navel, while standing relaxed and breathing out normally — don't suck in.
- Hip (women only): Measure around the widest part of your hips and buttocks.
- Height: Measure barefoot, standing straight against a wall.
Use a flexible cloth or vinyl tape measure, keep it snug against the skin without compressing it, and take each measurement two or three times to average out small errors.
Body Fat Percentage vs BMI
BMI and body fat percentage answer different questions. BMI simply asks whether your weight is proportionate to your height, without knowing anything about what that weight is made of. Body fat percentage asks a more direct question: how much of you is fat? This matters most for people at the extremes — a muscular athlete can have a "high" BMI while carrying very little fat, and an older adult with reduced muscle mass can have a "normal" BMI while carrying a higher fat percentage than expected. Using both numbers together, alongside how your clothes fit and how you feel, gives a fuller picture than either one alone.
Other Ways to Measure Body Fat
- Skinfold calipers: A trained assessor pinches skin at several sites and uses the thickness to estimate body fat; accuracy depends heavily on the assessor's skill.
- Bioelectrical impedance scales: Send a small electrical current through the body; convenient but sensitive to hydration levels, which can skew results by several percentage points.
- DEXA scan: A medical-grade full-body scan considered one of the gold standards for body composition, typically available only at specialised clinics.
- Hydrostatic (underwater) weighing: Highly accurate but requires specialised lab equipment and full submersion.
The Navy tape method sits in a strong middle ground: far more accessible than a DEXA scan or underwater weighing, while generally more consistent than bioelectrical impedance scales that fluctuate with hydration.
Tips to Improve Your Body Fat Percentage
- Prioritise protein and strength training. Adequate protein intake combined with resistance training helps preserve or build lean muscle while you lose fat, rather than losing muscle along with it.
- Keep a moderate calorie deficit. Very aggressive deficits often burn muscle along with fat; a gradual, sustainable deficit tends to preserve more lean mass.
- Stay consistent with cardio. Regular cardiovascular activity supports overall calorie balance and heart health alongside strength work.
- Sleep and manage stress. Poor sleep and chronic stress both disrupt hormones that influence fat storage and appetite.
- Re-measure periodically, not daily. Body fat percentage shifts slowly; measuring every few weeks under similar conditions gives a much clearer trend than daily checks.
Final Thoughts
Whether you use the tape-based Navy method for a precise reading or the quick BMI-based estimate for a rough number, tracking your body fat percentage over time — rather than obsessing over a single reading — is the most useful way to use this tool. Recheck every few weeks under consistent conditions, and pair the trend with how you feel, how your clothes fit, and your performance in the gym for the fullest picture of your progress.
Frequently Asked Questions
The U.S. Navy tape-measurement method is generally accurate to within about 3 to 4 percent of body fat compared to lab methods like DEXA scans, making it one of the most reliable options you can do at home with just a tape measure.
For men, a body fat percentage between roughly 14 and 24 percent is generally considered fit to acceptable. For women, the comparable healthy range is roughly 21 to 31 percent, since women naturally carry more essential fat than men.
Men need their neck, waist and height. Women need their neck, waist, hip and height. All measurements should be taken with a flexible tape measure, snug against the skin but not compressing it.
Body fat percentage directly measures how much of your body is fat versus lean mass, while BMI only compares weight to height. For people with high muscle mass or older adults, body fat percentage generally gives a more accurate picture of health than BMI alone.
For the Navy method, waist is typically measured at the narrowest point of the torso, usually level with or just above the belly button, while standing relaxed and breathing out normally.
No, this calculator is intended for adults. Body fat distribution and healthy ranges differ significantly in growing children and teenagers, who should be assessed using paediatric-specific methods and guidance from a doctor.
The Navy method uses actual body measurements and tends to be more precise, while the BMI-based estimate only uses weight, height and age, so it can be less accurate for very muscular or very lean individuals. If the two results differ a lot, trust the Navy tape measurement over the quick estimate.
A gradual combination of a modest calorie deficit, regular strength training to preserve muscle, adequate protein intake, consistent cardiovascular exercise and good sleep is the safest and most sustainable way to reduce body fat percentage over time.