Body Fat Calculator On-device
US Navy circumference method — estimates body-fat percentage from tape measurements, entirely on your device.
Tape-measure estimate only — typical error versus DXA is ±3–4 percentage points; the formula tends to underestimate body fat in muscular or high-BMI people and overestimate it in very lean women. Informational only, not medical advice.
Free US Navy body-fat calculator using tape measurements of waist, neck and hip, with the typical error band disclosed and a four-formula ideal-weight comparison. Works entirely on your device.
About this tool
What you provide
- Sex, height, waist and neck measurements — plus hip for women — in centimetres or inches
- Age, optionally
What you get
- Estimated body-fat percentage by the US Navy circumference method
- Ideal-weight figures from four published formulas (Devine, Robinson, Miller, Hamwi) and the BMI healthy range for your height
Limits
- A tape-measure estimate, not a scan — typical error versus a DXA scan is about ±3–4 percentage points.
- The formula tends to underestimate body fat in muscular or high-BMI people and overestimate it in very lean women.
- Informational only, not medical advice; it is derived from adult data and does not apply under 18.
How to use it
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Choose units and sex
Press Metric (cm) or Imperial (in), then Male or Female — the female formula adds a hip measurement.
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Take the tape measurements
Enter your height, your waist measured at navel level with the tape horizontal, your neck measured just below the larynx, and for women the hips at their widest point; the optional age field sits with them.
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Read the estimate
The estimated body-fat percentage appears on a 0–60% scale with the typical ±3–4 percentage-point error against a DXA scan stated beneath it; an age under 18 shows the clinician note instead.
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Compare ideal weights
Below the estimate, the Devine, Robinson, Miller and Hamwi formulas and the BMI healthy range are listed together for your height, with no single one presented as the answer.
Frequently asked questions
How does the body fat calculator work?
It uses the US Navy circumference method, estimating your body-fat percentage from tape measurements you enter, calculated entirely on your device.
How accurate is the US Navy method?
It's an estimate from body measurements, not a clinical scan, so results can differ from more precise methods; for an accurate assessment, consult a clinician.
Does it upload my measurements?
No, everything is computed on your device and nothing is sent anywhere.