Body Fat Calculator
A body fat calculator estimates the percentage of your body weight that is fat, using tape-measure circumferences rather than a scale. Toolverge uses the U.S. Navy method (Hodgdon & Beckett, 1984), the standard formula behind most free online body-fat calculators, which needs only waist, neck, and height for men, plus hip for women.
Educational estimate only. Results are not medical, legal, or financial advice. Confirm important decisions with a qualified professional.
How it works
- Choose your gender.
- Enter height, neck, and waist in centimeters (plus hip for women).
- Read the estimated body fat percentage on the tape.
Formula Men: 495/(1.0324 − 0.19077×log₁₀(waist−neck) + 0.15456×log₁₀(height)) − 450 · Women adds hip and uses different constants.
Frequently asked questions
How accurate is the U.S. Navy method?
It’s typically within a few percentage points of more precise methods like DEXA scanning for most body types, which is why it’s the standard for free tape-measure calculators — but it’s an estimate, not a clinical measurement.
Why does it need a hip measurement for women but not men?
The Navy method uses separate formulas for each gender; the women’s version was derived using hip circumference as an additional predictor.
What if my waist is smaller than my neck?
The formula requires waist to exceed neck (it takes the log of their difference) — if that isn’t true for you, this method can’t produce an estimate.
Can I use inches instead of centimeters?
Convert inches to centimeters first (multiply by 2.54) — the Unit Converter tool does this.
Is this a medical measurement?
No — it’s a tape-measure estimate for general fitness tracking, not a diagnosis.