Estimate your body fat percentage with the U.S. Navy circumference method.
All measurements stay in your browser.
How do you calculate body fat percentage using the Navy method?
For men: %BF = 495 ÷ (1.0324 − 0.19077·log₁₀(waist − neck) + 0.15456·log₁₀(height)) − 450, with measurements in centimetres; women add hip and use female constants. A man 180 cm tall with a 38 cm neck and 90 cm waist measures about 20%. This circumference method is a quick estimate; DEXA scans are more precise.
Understanding your result
The Navy method is a quick estimate. Methods like DEXA scans or skinfold calipers are more precise but need equipment.
Formula and method
Men: %BF = 495 ÷ (1.0324 − 0.19077·log₁₀(waist − neck) + 0.15456·log₁₀(height)) − 450. Women add hip and use the female constants. All measurements in centimetres.
Assumptions and limitations
The Navy method is a general estimate, not medical advice, and results vary by individual and measuring technique. It relies on circumference formulas rather than direct measurement, so it is less precise than methods like DEXA or skinfold calipers. Use it to track a trend, and consult a qualified professional for health decisions.
Worked example
A man 180 cm tall with a 38 cm neck and 90 cm waist has an estimated body fat of about 20%.
How to use this tool
- Choose your gender and unit system.
- Measure your height, neck and waist (and hips for women).
- Optionally add your weight to see fat and lean mass.
- Press Calculate.
Common mistakes to avoid
- Measuring the waist at the belt line rather than the navel.
- Mixing metric and imperial measurements.
About the Body Fat Percentage Calculator
The Body Fat Calculator estimates your body fat percentage from simple tape measurements using the U.S. Navy circumference formula — no special equipment needed.
Who should use this tool
People who want a quick body fat estimate from tape measurements alone, using the U.S. Navy circumference method, without a scan or calipers. Useful for tracking a trend over time at home, provided measurements are taken consistently at the same points.
Benefits
- Estimates body fat from simple tape measurements
- Uses the established U.S. Navy circumference formula
- Needs no scan, calipers or special equipment
- No app to install and no email required
Practical use cases
- Getting a quick body fat estimate at home
- Tracking a trend across regular measurements
- Comparing progress at home without any gym equipment
- Adding context to weight or BMI figures
Frequently asked questions
How accurate is the Navy body fat formula?
It’s typically within a few percentage points of a DEXA scan for most people, which is good enough for tracking trends over time.
Where exactly do I measure my waist?
Measure around the navel for men and at the narrowest point for women, keeping the tape level and snug but not tight.
How can I make my measurements more consistent?
Measure at the same time of day, keep the tape level and snug without compressing the skin, and use the same landmarks each time. Because the formula is sensitive to circumference, small differences in placement change the result. Consistency matters more than perfection when you are tracking a trend over time.
Why do men and women use different inputs?
The U.S. Navy formula uses neck and waist for men, and adds hip for women, with different constants for each. This reflects average differences in where body fat is distributed. Entering the measurements the tool asks for, in centimetres, produces the estimate designed for your sex.