Body Fat Calculator

Estimate your body fat percentage with the U.S. Navy tape measure method.

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Units

Sex

Age

years

Height

Height (feet)

Inches

Weight

Neck circumference

Waist circumference (at the navel)

Hip circumference (widest point)

Enter your values to see the result.

These results are estimates for general information, not medical advice. Body shape, muscle mass, age, ethnicity and health conditions all affect what is right for you, so talk to a doctor or dietitian before making health decisions.

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How this calculation works

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Formula: With measurements in cm, Navy body fat %: men 495 / [1.0324 − 0.19077log10(waist − neck) + 0.15456log10(height)] − 450; women 495 / [1.29579 − 0.35004log10(waist + hip − neck) + 0.221log10(height)] − 450. Fat mass = weight × body fat % / 100.
Variables: Units: Metric, Imperial
Sex: Male, Female
Age
Height
Height (feet)
Inches
Weight
Weight
Neck circumference
Neck circumference
Waist circumference (at the navel)
Waist circumference (at the navel)
Hip circumference (widest point)
Hip circumference (widest point)
Units: Age: years
Height: cm
Height (feet): ft
Inches: in
Weight: kg
Weight: lb
Neck circumference: cm
Neck circumference: in
Waist circumference (at the navel): cm
Waist circumference (at the navel): in
Hip circumference (widest point): cm
Hip circumference (widest point): in
Example: A man who is 175 cm tall with a 38 cm neck and an 85 cm waist has about 17% body fat by the Navy method, in the "fitness" range. Measuring again every few weeks under the same conditions shows whether fat is really going down.
Assumptions: These results are estimates for general information, not medical advice. Body shape, muscle mass, age, ethnicity and health conditions all affect what is right for you, so talk to a doctor or dietitian before making health decisions.
Source: ToolzHive calculation guide and calculator implementation. External reference verification is pending.
Last reviewed: Review date not yet recorded.

Methodology & References

The method depends on the selected model and input options. Review the assumptions and references above before interpreting the result.

Choose your units and sex, then enter your age, height and weight.
Measure your neck just below the larynx, your waist at the navel and, for women, your hips at the widest point. Keep the tape level and snug but not tight.
Read your body fat percentage, category and the fat versus lean mass breakdown.

Interpretation and limitations

How accurate is the U.S. Navy method? It is usually within about 3–4 percentage points of lab methods like DEXA scans for most people. Accuracy depends on careful, consistent measuring, so take each measurement two or three times.
What is a healthy body fat percentage? For adults, the American Council on Exercise lists about 14–24% as fitness to average for men and 21–31% for women. Essential fat, the minimum needed for health, is about 2–5% for men and 10–13% for women.
Why measure body fat instead of BMI? BMI cannot tell muscle from fat, so muscular people can be labelled overweight. Body fat percentage describes your body composition more directly.

References

External reference verification is pending. The formula and examples describe the current ToolzHive implementation.

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How to use the Body Fat Calculator

The body fat calculator estimates what share of your weight is fat, using the U.S. Navy circumference method: measurements of your neck, waist and (for women) hips, together with your height. It also shows a BMI-based estimate for comparison, splits your weight into fat mass and lean mass, and places your result in the American Council on Exercise categories from essential fat to obese.

1 Choose your units and sex, then enter your age, height and weight.
2 Measure your neck just below the larynx, your waist at the navel and, for women, your hips at the widest point. Keep the tape level and snug but not tight.
3 Read your body fat percentage, category and the fat versus lean mass breakdown.

Example and practical tips

A man who is 175 cm tall with a 38 cm neck and an 85 cm waist has about 17% body fat by the Navy method, in the "fitness" range. Measuring again every few weeks under the same conditions shows whether fat is really going down.

Frequently asked questions

How accurate is the U.S. Navy method?

It is usually within about 3–4 percentage points of lab methods like DEXA scans for most people. Accuracy depends on careful, consistent measuring, so take each measurement two or three times.

What is a healthy body fat percentage?

For adults, the American Council on Exercise lists about 14–24% as fitness to average for men and 21–31% for women. Essential fat, the minimum needed for health, is about 2–5% for men and 10–13% for women.

Why measure body fat instead of BMI?

BMI cannot tell muscle from fat, so muscular people can be labelled overweight. Body fat percentage describes your body composition more directly.

How to Use Body Fat Calculator
Estimate your body fat percentage with a tape measure using the U.S. Navy method, plus fat mass, lean mass and your ACE body fat category. Free calculator.