Body Fat Calculator
Estimate your body fat percentage with the U.S. Navy method using simple tape measurements.
What is a body fat calculator?
A body fat calculator estimates the percentage of your body weight that is made up of fat, using the US Navy circumference method. It needs a few simple tape measurements — height, neck, and waist (plus hips for women) — and then applies the Navy formula, developed by the US Navy from hydrostatic weighing data. Unlike BMI, which only compares weight to height, body fat percentage distinguishes fat from muscle, giving a much more useful picture of body composition for most people. The tool also converts your body fat percentage into fat mass and lean body mass, and labels the result into a category such as essential fat, athletic, fit and healthy, average or obese. It is a practical, equipment-free screening tool that you can use at home with no more than a tape measure, and it runs entirely in your browser. Remember it is an estimate, not a clinical measurement.
Example
For a male with a height of 180 cm, a neck of 38 cm and a waist of 92 cm, the tool returns a body fat percentage of about 21.2%, which falls into the average category, with the fat mass and lean mass shown alongside.
Who is this body fat calculator for?
This body fat calculator uses the US Navy tape-measure method, needing only height, neck and waist (plus hips for women). It suits anyone who wants a quick estimate of body-fat percentage without special equipment.
- Men: Men often use a body fat calculator for men to judge body composition and lean mass. It uses height, neck and waist, and the reference ranges differ from those used for women.
- Women: Women use a body fat calculator for women to estimate body-fat percentage, adding a hip measurement. Healthy reference ranges differ from men because women naturally carry more essential fat.
- Seniors: Seniors may track body fat to keep an eye on lean mass, which naturally declines with age. Estimates vary, so follow the trend rather than a single reading.
- Teens: Teens can use a body fat calculator for teens to understand changes during growth, though age- and sex-specific charts are a better reference than adult ranges.
Body fat chart and table — example values from the US Navy formula
These estimates are worked out with the same Navy formula as this calculator. Reference categories are general ranges, and body-fat estimates carry error.
| Reference person | Waist | Body fat | Reference category |
|---|---|---|---|
| Men (175 cm, neck 40 cm) | 80 cm | 11.1% | Athletic |
| Men (175 cm, neck 40 cm) | 88 cm | 17.7% | Fit / healthy |
| Men (175 cm, neck 40 cm) | 96 cm | 23.4% | Average |
| Men (175 cm, neck 40 cm) | 104 cm | 28.5% | Obese |
| Women (165 cm, neck 32 cm, hip 92 cm) | 62 cm | 19.0% | Athletic |
| Women (165 cm, neck 32 cm, hip 92 cm) | 74 cm | 25.4% | Average |
Common use cases
- Tracking fat-loss progress beyond the scale, since muscle mass can skew weight results.
- Setting a body-composition goal and seeing how far you are from it.
- Getting a rough estimate for general fitness screening when you have no special equipment.
- Comparing body fat with BMI to understand your overall composition.
Pro tips
- Measure consistently — same time of day, relaxed posture, and the tape snug but not compressing the skin.
- For women, the hip measurement is required by the Navy formula, so take it at the widest point.
- The method is accurate to roughly ±3-4 percentage points versus a DEXA scan, so treat it as a trend.
- Combine with BMI and how you feel, since body fat is only one part of fitness.
How to use this body fat calculator
- Select your gender.
- Enter your height, neck and waist circumferences in centimetres.
- Women: also enter your hip circumference. Men: leave it blank.
- Click Calculate body fat to see your body fat percentage, fat mass and lean mass.
Measure around the neck below the larynx, at the widest point of the waist (navel for men), and around the widest part of the hips for women.
How the US Navy method works
Body fat % (men) = 495 / (1.0324 − 0.19077·log₁₀(waist − neck) + 0.15456·log₁₀(height)) − 450 Body fat % (women) = 495 / (1.29579 − 0.35004·log₁₀(waist + hip − neck) + 0.22100·log₁₀(height)) − 450
Fat mass is body fat % × weight; lean mass is the remainder. A healthy range is roughly 10–20% for men and 18–28% for women.
FAQ
What is the US Navy method?
A tape-measure formula that estimates body fat percent from height, neck and waist girths (and hip girth for women).
How accurate is it?
Usually within a few percentage points of lab methods. Measure consistently for the most useful trends.
Is it private?
Yes — it runs entirely in your browser.
What is body fat percentage?
It is the share of your total body weight that is fat tissue, as opposed to muscle, bone and other lean mass.
What is the US Navy method?
A body fat formula that uses tape measurements of height, neck and waist (and hips for women) to estimate body density and then body fat percentage. It requires no special equipment.
How accurate is it?
For most healthy adults it is accurate to within about 3-4 percentage points compared with a DEXA scan, making it a good screening tool rather than a precise measurement.
What are healthy body fat ranges?
Typical healthy ranges are roughly 14-18% for men and 21-25% for women, though this varies with age and fitness level.
Why does it need hips for women?
The Navy formula uses a different measurement set for women — waist plus hips minus neck — so the hip circumference is required for the calculation.
What is fat mass versus lean mass?
Fat mass is your weight multiplied by your body fat percentage; lean mass is the rest, including muscle, bone and organs.
Is BMI the same as body fat?
No. BMI only uses height and weight, so it can misclassify muscular people. Body fat distinguishes fat from muscle for a clearer picture.
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