Body Fat Calculator
US Navy body fat calculator: height, neck and waist, plus hips for women, give body fat percent from a tape measure, or use BMI, age and sex instead. How it works
Use the Body Fat Calculator
About the Body Fat Calculator
To calculate body fat with a tape measure, enter your height, neck and waist, plus your hips if you are a woman. The calculator applies the U.S. Navy circumference equations. A man 175 cm tall with a 38 cm neck and an 85 cm waist comes out at 16.9%, in the Fitness band (14 to under 18% for men). In the studies behind the equations, the standard error against underwater weighing was 3.5 percentage points for men and 3.7 for women. Without a tape, the BMI method (Deurenberg, 1991) estimates body fat from weight, height, age and sex.
Body fat categories the calculator uses
| Category | Men | Women |
|---|---|---|
| Below essential fat | under 2% | under 10% |
| Essential Fat | 2% to under 6% | 10% to under 14% |
| Athletes | 6% to under 14% | 14% to under 21% |
| Fitness | 14% to under 18% | 21% to under 25% |
| Acceptable | 18% to under 25% | 25% to under 32% |
| Obese | 25% or more | 32% or more |
The cut-offs follow the American Council on Exercise chart: essential fat 2 to 5% for men and 10 to 13% for women, athletes 6 to 13% and 14 to 20%, fitness 14 to 17% and 21 to 24%, acceptable 18 to 24% and 25 to 31%, obesity above that. The calculator decides the band on the one-decimal figure it shows, so 5.9% is still essential fat for a man. A band describes a range. It is not a diagnosis.
Body fat by waist size for a man 175 cm tall with a 38 cm neck
| Waist | Estimated body fat | Category |
|---|---|---|
| 75 cm | 8.4% | Athletes |
| 80 cm | 12.9% | Athletes |
| 85 cm | 16.9% | Fitness |
| 90 cm | 20.7% | Acceptable |
| 95 cm | 24.1% | Acceptable |
| 100 cm | 27.3% | Obese |
| 105 cm | 30.2% | Obese |
| 110 cm | 33% | Obese |
Each row is the calculator’s result for those measurements. A different height or neck moves every figure.
Body fat by waist size for a woman 165 cm tall with a 33 cm neck and 100 cm hips
| Waist | Estimated body fat | Category |
|---|---|---|
| 60 cm | 21.7% | Fitness |
| 65 cm | 24.3% | Fitness |
| 70 cm | 26.9% | Acceptable |
| 75 cm | 29.4% | Acceptable |
| 80 cm | 31.9% | Acceptable |
| 85 cm | 34.3% | Obese |
| 90 cm | 36.6% | Obese |
| 95 cm | 38.9% | Obese |
| 100 cm | 41.2% | Obese |
Each row is the calculator’s result for those measurements. The women’s equation uses waist + hips − neck, so larger hips raise the figure as well.
Navy body fat chart for men with a 15 in neck
| Waist | 5 ft 4 in | 5 ft 7 in | 5 ft 10 in | 6 ft 1 in |
|---|---|---|---|---|
| 30 in | 11.5% | 10.2% | 8.9% | 7.8% |
| 32 in | 16% | 14.7% | 13.4% | 12.2% |
| 34 in | 20.1% | 18.7% | 17.4% | 16.2% |
| 36 in | 23.8% | 22.4% | 21.1% | 19.9% |
| 38 in | 27.3% | 25.9% | 24.5% | 23.2% |
| 40 in | 30.5% | 29.1% | 27.7% | 26.4% |
| 42 in | 33.5% | 32% | 30.6% | 29.3% |
Each cell is the calculator’s result in inches for that height, a 15 in neck and the waist in the row. The men’s equation depends on waist minus neck, so a 16 in neck with a 37 in waist reads the same as 15 in with 36 in.
Navy body fat chart for women with a 13 in neck and 38 in hips
| Waist | 5 ft 1 in | 5 ft 4 in | 5 ft 7 in | 5 ft 10 in |
|---|---|---|---|---|
| 26 in | 25.8% | 23.7% | 21.7% | 19.8% |
| 28 in | 28.5% | 26.4% | 24.3% | 22.4% |
| 30 in | 31.1% | 28.9% | 26.9% | 25% |
| 32 in | 33.6% | 31.5% | 29.4% | 27.5% |
| 34 in | 36.1% | 33.9% | 31.9% | 29.9% |
| 36 in | 38.6% | 36.4% | 34.3% | 32.3% |
Each cell is the calculator’s result in inches for that height, a 13 in neck, 38 in hips and the waist in the row. The women’s equation depends on waist + hips − neck, so the 30 in row also fits a 28 in waist with 40 in hips.
How to use this tool
- Pick U.S. Navy (tape) or BMI (weight, age). The BMI method needs height, weight, age and sex, and no tape measurements.
- Pick Metric (cm) or Imperial (inches, with height in feet and inches). Switching shows each field in the other unit and leaves the values you typed unchanged.
- Select Male or Female. The Hip field appears for Female.
- Measure your neck just below the larynx (Adam’s apple), with the tape sloping slightly downward to the front.
- Measure your waist at the navel if you are a man, or at the narrowest point of the abdomen if you are a woman. Women also measure the hips at their widest point.
- Keep the tape snug without pressing into the skin, and measure at the same spots each time so that readings can be compared.
- Optionally enter your weight: the page splits it into fat mass and lean mass at the body fat shown.
Frequently asked questions
- How do I calculate body fat with a tape measure?
- Measure your height, neck and waist, and your hips if you are a woman, then enter them here. For men the equation is 495 ÷ (1.0324 − 0.19077 × log10(waist − neck) + 0.15456 × log10(height)) − 450, with every length in centimeters. Women use waist + hips − neck with different constants: 495 ÷ (1.29579 − 0.35004 × log10(waist + hips − neck) + 0.22100 × log10(height)) − 450.
- How accurate is the tape measure method for body fat?
- In the studies that produced the equations, the standard error against underwater weighing was 3.52 percentage points for 602 Navy men and 3.72 for 214 Navy women. A careless tape adds to that: for the example man, a waist read 1 cm too large moves the result from 16.9% to 17.7%. The BMI method is looser: Deurenberg and colleagues give a standard error of 4.1 points, and it slightly overestimates body fat in obese people.
- What is a good body fat percentage for men and women?
- The calculator does not judge that. On the American Council on Exercise chart it follows, 14 to 17% for men and 21 to 24% for women is labeled Fitness, and 18 to 24% for men and 25 to 31% for women is labeled Acceptable. The chart describes ranges. What is right for you is a question for a doctor.
- Why do women need a hip measurement?
- The women’s equation was fitted separately, on 214 Navy women, and the regression kept hip circumference as a predictor. It uses waist + hips − neck where the men’s equation uses waist − neck. The Hip field appears when you select Female.
- Does this tell me if I pass the Navy body composition assessment?
- No. It applies the Navy’s 1984 research equations (Hodgdon and Beckett, Naval Health Research Center) and shows a general label from a civilian fitness chart, but no Navy pass or fail limit. The Navy’s current assessment is set by its own instructions and may measure or score differently. The Navy estimate needs no body weight.
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