Body Fat Calculator
Estimate body fat percentage with the US Navy method using tape measurements. Track your fitness progress accurately for men and women.
Body fat
12.3%
Category
Athletic
Ideal fat range
10–18%
for general health
US Navy method. Tape should be snug but not tight; measure the neck just below the larynx. Estimates vary ±3%.
How it works
Navy method (male): 495 ÷ (1.0324 − 0.19077·log₁₀(w−n) + 0.15456·log₁₀(h)) − 450, in inches.
Example: waist 90 cm, neck 40 cm, height 178 cm → ≈ 12.3%.
Last updated: August 2026
How this calculator is verified
Checked by True Calculator automated test suite on
- Formula verified against a published worked example in the automated test suite
- Edge cases (zero, negative, boundary and unit-mismatch inputs) covered by unit tests
The full verification method is on our how we verify page. Found an error? Tell us and we will re-check it.
When to Use This Calculator
Use the body fat calculator when you want a fuller picture than BMI alone — two people of the same weight can carry very different fat percentages. It is popular with gym members in India who track fat loss instead of just scale weight, with trainers doing monthly progress reviews, and with athletes preparing for a season. The US Navy method needs only a tape measure: waist, neck and, for women, hip circumference, so it works at home without a body fat scale or a gym's callipers. Weight-loss programmes use the percentage to set realistic milestones, and people on a lean-gains phase use it to confirm they are adding muscle, not fat. Re-measure on the same day and time each month so the numbers stay comparable.
How to Use This Calculator
- Step 1: Select your sex, then enter your height in centimetres.
- Step 2: Measure your waist at navel level and your neck below the larynx, both in centimetres.
- Step 3: If you are female, also measure the hips at their widest point and enter that value.
- Step 4: Calculate and read your estimated body fat percentage, its category and your lean body mass in kilograms.
Worked Example
A 30-year-old man in Hyderabad who is 175 cm tall measures his waist at 96 cm and his neck at 40 cm, keeping the tape snug without pressing the skin. The US Navy equation converts the measurements to inches and returns about 17 percent body fat, which places him in the fit category for men. A woman of 162 cm with a waist of 95 cm, hips of 115 cm and neck of 34 cm gets about 21 percent, within the fit range for women. Readings drift when the tape is loose, so keep the position identical each time.
Tips and Common Mistakes
- •Tip 1: Take measurements at the same time of day, ideally in the morning, because waist size changes through the day with food and posture.
- •Tip 2: Re-measure every four to six weeks rather than weekly, since body fat changes slowly and tape error can hide real progress.
- •Tip 3: Track the trend rather than a single reading, because the navy formula is an estimate with an error of a few percentage points.
- ✗Mistake 1: Skipping the hip measurement when entering data as a woman, which the calculator needs for the female equation.
- ✗Mistake 2: Pulling the tape tight or measuring over clothing, which changes the readings and can swing the result by several percent.
Frequently Asked Questions
How accurate is the US Navy body fat method?
Within about ±3% of hydrostatic weighing when measurements are taken correctly. The tape must be snug, and the neck is measured just below the larynx.
What is a healthy body fat percentage?
For men, 10–20% is considered fit and 6–13% is athletic. For women, 18–28% is fit and 14–21% is athletic, since women need more essential fat.
Why is BMI different from body fat percentage?
BMI only uses height and weight, so muscular people score high. Body fat percentage measures actual fat, making it more accurate for athletic builds.
What is visceral fat and why does it matter?
Visceral fat wraps around organs inside the belly. Even at a normal body fat percentage, high visceral fat raises the risk of heart disease and diabetes.
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