How to Measure Body Fat Percentage
By the Calculator.hair team · Updated · 6 min read
Short answer
The easiest home method is the US Navy tape test: measure your height, neck and waist (plus hips for women) and enter them in the Navy formula. A man 5 ft 10.5 in tall with a 15.5 in neck and 37.5 in waist comes out at 15.3% body fat. On the ACE scale, 18% to 24% is average for men and 25% to 31% for women.
Key takeaways
- Body fat percentage is fat mass divided by total body weight; the rest is lean mass.
- The US Navy method needs only a tape measure: neck and waist for men, plus hips for women.
- ACE norms put average body fat at 18% to 24% for men and 25% to 31% for women.
- DEXA, hydrostatic weighing and air displacement are lab methods; calipers and smart scales are cheaper but depend heavily on technique and conditions.
- Whatever method you pick, use the same one under the same conditions to track change over time.
How do you measure body fat at home?
Use a flexible tape measure and the US Navy circumference method. It estimates body fat from a few body measurements, needs no special equipment and takes about five minutes. The equations were developed at the Naval Health Research Center in the 1980s by Hodgdon and Beckett and are still the basis of most online body fat calculators, including ours.
Body fat percentage means the share of your total weight that is fat. If you weigh 150 pounds and carry 30 pounds of fat, your body fat is 20%. Everything else (muscle, bone, organs, water) is called lean body mass.
- Height: stand straight against a wall without shoes.
- Neck: measure just below the larynx (Adam's apple), with the tape sloping slightly down toward the front.
- Waist, men: measure horizontally at the navel.
- Waist, women: measure at the narrowest point of the natural waist.
- Hips, women only: measure around the widest part of the buttocks.
- Keep the tape snug against bare skin without pressing in, breathe out normally, and take each measurement two or three times.
What does a worked example look like?
Example 1, a man: age 25, 152 pounds, 5 feet 10.5 inches tall, 15.5-inch neck and 37.5-inch waist. Converted to centimeters, waist minus neck is 55.88 cm and height is 179.07 cm. The formula gives 15.3% body fat. That is 23.2 pounds of fat and 128.8 pounds of lean mass, which falls in the ACE "fitness" band of 14% to 17%.
Example 2, a woman: age 35, 140 pounds, 5 feet 5 inches tall, 13-inch neck, 30-inch waist and 38-inch hips. The formula gives 28.3% body fat, or 39.6 pounds of fat and 100.4 pounds of lean mass. That is in the ACE "average" band of 25% to 31%.
Both results are what our calculator returns for these inputs. In the male example, a waist half an inch smaller or larger moves the result to 14.2% or 16.3%, so measure carefully and repeat.
What is a healthy body fat percentage?
The most widely quoted chart comes from the American Council on Exercise (ACE). It is a set of fitness norms rather than medical cut-offs, and there is no single official "healthy" body fat percentage from the CDC or WHO. Women carry more essential fat than men, which is why every band is higher for women.
Essential fat is the minimum needed for normal body function, found in nerves, bone marrow and organs. Going below it is not a fitness goal; it is unhealthy.
| ACE category | Women | Men |
|---|---|---|
| Essential fat | 10% to 13% | 2% to 5% |
| Athletes | 14% to 20% | 6% to 13% |
| Fitness | 21% to 24% | 14% to 17% |
| Average | 25% to 31% | 18% to 24% |
| Obese | 32% and above | 25% and above |
How does the Army tape test differ?
Since 2024, the US Army has used a one-site tape test: it measures only the abdomen at the navel and combines it with body weight. Army Directive 2023-11 replaced the older multi-site method (neck and waist for men, plus hips for women).
The equations are: men, body fat % = −26.97 − 0.12 × weight (lb) + 1.99 × abdomen (in); women, body fat % = −9.15 − 0.015 × weight (lb) + 1.27 × abdomen (in). For a 21-year-old man who weighs 165 pounds with a 36-inch abdomen, that gives 24.9%, which the Army rounds to 25%. His age group's limit is 22%, so he would not meet the standard. The Army body fat calculator applies the limits below by age and sex; check current Army guidance for any official purpose.
| Age | Men, maximum | Women, maximum |
|---|---|---|
| 17 to 20 | 20% | 30% |
| 21 to 27 | 22% | 32% |
| 28 to 39 | 24% | 34% |
| 40 and over | 26% | 36% |
What other ways can you measure body fat?
Several other methods exist, ranging from lab tests to bathroom scales. None is perfect, and different methods can give different numbers for the same person, so compare readings only within one method.
- DEXA (dual-energy X-ray absorptiometry): a low-dose X-ray scan that separates fat, lean tissue and bone, and shows where fat sits. It is widely used as a reference method in research. It costs money and needs a clinic or lab.
- Hydrostatic (underwater) weighing: compares your weight on land and fully submerged to calculate body density. Long used as a lab standard, it requires breathing out fully underwater.
- Air displacement plethysmography (Bod Pod): measures body volume by air displacement in a sealed chamber and works on the same density principle as underwater weighing.
- Skinfold calipers: pinch a fold of skin and fat at set sites and plug the thicknesses into an equation such as Jackson and Pollock. Results depend heavily on the tester's skill.
- Bioelectrical impedance analysis (BIA): smart scales and handheld devices pass a weak current through the body; fat conducts less than water-rich lean tissue. Readings shift with hydration, meals and exercise, so measure at the same time of day.
- Waist circumference alone: not a body fat percentage, but the NHLBI uses a waist above 40 inches for men or 35 inches for women as a marker of higher health risk.
How does body fat relate to lean body mass and BMI?
Lean body mass is total weight minus fat mass. Once you know your body fat percentage, subtract the fat: our male example has 128.8 pounds of lean mass. If you don't have a body fat number, the lean body mass calculator estimates it from height and weight with the Boer, James and Hume formulas; for the same man (5 ft 10.5 in, 152 lb) they give 118.7 to 125.4 pounds.
BMI uses only height and weight, so it cannot tell whether extra weight is fat or muscle. Body fat percentage fills that gap. Our guide to what a healthy BMI is covers when BMI is misleading, and how much protein you need matters if your goal is to keep lean mass while losing fat.
Calculators in this guide
Frequently asked questions
How accurate is the Navy body fat method?
It is an estimate built from population data, so an individual result can differ from a lab measurement. It is most useful for tracking change over time with consistent measurements.
What is the simplest body fat percentage formula?
Body fat % = fat mass ÷ total weight × 100. Since fat mass can't be weighed directly, formulas like the Navy method estimate it from circumferences instead.
Where do I measure my waist for the Navy formula?
Men measure horizontally at the navel. Women measure at the narrowest point of the natural waist and also measure the hips at their widest point.
Is DEXA better than a smart scale?
DEXA is a lab method used as a research reference and also shows where fat is stored. Smart scales use bioelectrical impedance, which shifts with hydration and recent meals, so they are better for trends than for a single precise number.
What body fat percentage is obese?
On the ACE chart, 25% or more for men and 32% or more for women. Medical diagnosis of obesity normally uses BMI of 30 or higher, often alongside waist size.
This guide is for education and is not medical advice. Talk to a doctor or other qualified health professional about your situation.