Body Fat (Navy Method)
The US Navy formula takes the waist-minus-neck girth and your height through logarithms to estimate fat percentage. The female version uses different coefficients.
Your numbers
Body fat
16.9%
What it means
16.9% falls inside the usual healthy range.
Formula
Body fat = 495 ÷ (1.0324 − 0.19077·log(Waist (cm)−Neck (cm)) + 0.15456·log(Height (cm))) − 450
This is an estimate with roughly 3–4 points of error — watch the trend rather than the absolute number.
What to enter
| Input | Default | Accepted range |
|---|---|---|
| Sex (M1 / F0)Where the formula splits by sex — enter 1 for male, 0 for female. | 1 | 0 ~ 1 |
| Height (cm)Height in centimetres; converted to metres inside the formula. | 175 | 100 ~ 250 |
| Waist (cm)Waist at navel height, measured after breathing out. | 85 | 40 ~ 200 |
| Neck (cm)Neck circumference at its narrowest point. | 38 | 20 ~ 80 |
Step by step
Quick reference table
Results when only Height (cm) changes and everything else stays put.
| Height (cm) | Body fat (%) |
|---|---|
| 100 | 34.1 |
| 131 | 25.7 |
| 175 | 16.9 |
| 250 | 6.6 |
What each result means
| Result | At default values |
|---|---|
| Body fat (%)The share of body weight that is fat. | 16.9 |
Common mistakes
This is an estimate with roughly 3–4 points of error — watch the trend rather than the absolute number.
Glossary
- Sex (M1 / F0)
- Where the formula splits by sex — enter 1 for male, 0 for female.
- Height (cm)
- Height in centimetres; converted to metres inside the formula.
- Waist (cm)
- Waist at navel height, measured after breathing out.
- Neck (cm)
- Neck circumference at its narrowest point.
- Body fat
- The share of body weight that is fat.
Frequently asked questions
Q. How is Body Fat (Navy Method) calculated?
Body fat = 495 ÷ (1.0324 − 0.19077·log(Waist (cm)−Neck (cm)) + 0.15456·log(Height (cm))) − 450 — The US Navy formula takes the waist-minus-neck girth and your height through logarithms to estimate fat percentage. The female version uses different coefficients.
Q. Can you walk through an example?
With Sex (M1 / F0) 1, Height (cm) 175, Waist (cm) 85, Neck (cm) 38, the answer is Body fat 16.9%.
Q. What do I need to enter?
Enter Sex (M1 / F0), Height (cm), Waist (cm), Neck (cm). The result recalculates as you type, and an empty box counts as zero.
Q. How much does the answer move if I change a number?
Changing only Height (cm) moves the answer to Height (cm) 100 → Body fat (%) 34.1 and Height (cm) 250 → Body fat (%) 6.6. The table below lays out five steps.
Q. How are the numbers rounded?
Money is shown to the nearest whole unit, percentages to one decimal place and everything else to two. What you see is rounded; the calculation itself carries the unrounded value forward.
Q. Anything to watch out for?
This is an estimate with roughly 3–4 points of error — watch the trend rather than the absolute number.
Related calculators
These calculators help you understand health figures; they do not replace diagnosis or prescription. See a clinician if you have symptoms.