—
Category
Body Fat Percentage Calculator
Scales only show total weight. Body fat percentage estimates how much of that weight is fat versus lean tissue. This calculator uses the US Navy circumference method: tape measurements of neck, waist and (for women) hips plus height. It is a practical field estimate used by many fitness programmes, not a clinical gold standard, but it gives a useful number without specialised equipment. Figures and examples are oriented toward European users, with euro amounts and metric units where relevant.
Please enter valid positive measurements. For women, hip is required.
Estimated body fat
—
How to Use the Body Fat Calculator
- Select sex and preferred units (centimetres or inches).
- Measure height, neck just below the larynx, and waist at navel level.
- Women: also measure hips at the widest point.
- Enter the values and calculate to see estimated body fat % and a general category.
Start with the inputs shown in the calculator and use the units or options that match your situation. Enter realistic values rather than estimates when you have the exact figures available. After you select Calculate, check the displayed result and the supporting breakdown. If you change an input, run the calculation again so the result reflects the updated assumptions. The tool is designed to make the process quick while keeping the underlying steps understandable.
Body Fat Calculator Formula Explained
US Navy Circumference Equations
For men: body fat % = 495 ÷ (1.0324 − 0.19077 × log₁₀(waist − neck) + 0.15456 × log₁₀(height)) − 450. For women: 495 ÷ (1.29579 − 0.35004 × log₁₀(waist + hip − neck) + 0.22100 × log₁₀(height)) − 450. All lengths must be in the same unit. The logarithms capture the non-linear relationship between girth and estimated fat. Results are sensitive to measurement technique; consistent tape placement improves repeatability.
The displayed result depends on the inputs you provide and the calculation method described on this page. Keeping the inputs consistent with the stated units is important because changing a unit, period, rate, date, or percentage can change the result significantly. The calculator performs the arithmetic automatically, while the explanation gives you enough context to understand what is being combined, converted, or compared. For estimates, treat the output as an indication based on your assumptions rather than as a guaranteed real-world outcome.
Body Fat Calculator Example Calculation
A man 180 cm tall with a 38 cm neck and 90 cm waist might see an estimated body-fat percentage in the mid-teens using the Navy method. A woman of similar height with neck, waist and hip measurements entered correctly will use the female equation, which includes hip circumference. Consistent morning measurements give more comparable trends over weeks.
This example is meant to show the order of the inputs and the way the final result is reached. In your own calculation, replace the example figures with your actual values and keep the same units throughout. A useful check is to change one input slightly and confirm that the result changes in a sensible direction. That simple check can help catch an incorrect unit, percentage, date, or other assumption before you rely on the result.
When to use this tool
Use this when you want a practical body-composition estimate without clinic equipment—useful for gym tracking across Europe. It is not a substitute for DXA or professional assessment when medical decisions are involved.
Key Features & Benefits of This Body Fat Calculator
- Built for real use — Use this when you want a practical body-composition estimate without clinic equipment—useful for gym tracking across Europe.
- Instant, free and private — runs entirely in your browser, no sign-up, nothing stored.
- Formula-accurate — US Navy Circumference Equations For men: body fat % = 495 ÷ (1.0324 − 0.19077 × log₁₀(waist − neck) + 0.15456 × log₁₀(height)) − 450.
- Works on any device — mobile or desktop, no app or installation needed.
Good to know
Tape placement matters: neck just below the larynx, waist at navel level, and for women hips at the widest point. Repeat measurements at the same time of day for trends that are meaningful in fitness tracking.
Body Fat Calculator — FAQs
How accurate is the Navy method?
It is an estimate with typical error of a few percentage points. Hydrostatic weighing, DXA or professional calipers are more precise when available.
When should I measure?
Morning, before eating, with the same tape tension each time produces more comparable results across sessions.
Why is hip required only for women?
The original Navy equations include hip circumference for women because it improved the statistical fit in the validation samples.
How accurate is the US Navy method compared to DEXA scans?
It typically comes within a few percentage points of clinical methods for most body types, though accuracy can drop for very lean or very heavy individuals.
The FAQs below address common questions about using this Body Fat Percentage Calculator. They also explain assumptions and situations where the result may need additional context. If your situation uses a different rule, local rate, institutional policy, or professional standard, use the relevant source alongside the calculator rather than treating a general estimate as a definitive answer.