Body Fat Calculator
Estimate body fat percentage with the US Navy circumference method, plus lean mass and category.
Your details
Measurements
Measured just below the larynx
At the navel for men, at the narrowest point for women
This calculator runs entirely on your device. Nothing you enter is uploaded, stored, or sold. How this works
Estimated body fat
18.0%
Above range
Includes your inputs, the full breakdown, and every row of the table.
Fat mass
33.2 lb
Lean body mass
151.8 lb
Waist-to-height ratio
0.49
Below 0.5 — low risk
Fat-free mass index
21.2
| Category | Range |
|---|---|
| Essential fat | 2% – 5% |
| Athletic | 6% – 13% |
| Fitness | 14% – 17% |
| Average | 18% – 24% |
| Obese | 25% – 70% |
What this means
- The US Navy circumference method is typically within 3-4 percentage points of a DEXA scan for people of average build, and less accurate at very high or very low body fat.
- Measure first thing in the morning, unflexed, with the tape snug but not compressing the skin. Consistency of technique matters more than absolute accuracy when tracking change.
How the body fat calculation works
The US Navy method estimates body fat from circumference measurements and height using a logarithmic regression developed for military body composition standards. It requires nothing but a tape measure, which is why it remains the most practical at-home option.
Track the trend, not the single number. Any field method carries several points of error, but that error is consistent for one person measuring the same way over time — so a reading that drops from 24% to 21% over three months is meaningful even if neither figure is exactly right.
Frequently asked questions
What is a healthy body fat percentage?
For men, roughly 10-20%; for women, 18-28%. Essential fat — the minimum required for physiological function — is about 3% for men and 10-12% for women.
Why is my BMI high but body fat normal?
BMI cannot distinguish muscle from fat. If you carry substantial lean mass, BMI overstates your risk while a circumference-based estimate reflects reality more closely.
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Disclaimer. This calculator is provided for general information and educational purposes only and does not constitute financial, tax, legal, medical, or engineering advice. Results are estimates based on the inputs you provide and the assumptions described above. Confirm any figure with a qualified professional before acting on it.