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Body Fat %

Estimate body fat percentage from measurements.

Free to use, no sign-up required. Body Fat % is one of 198 tools built into Xenition, alongside a chat that can use them for you.

Estimates body fat percentage from a few tape-measure readings using the US Navy circumference method, with no scale or calipers needed. The result is an estimate, not medical advice.

How to use Body Fat %

  1. Choose Male or Female.
  2. Enter Height, Neck and Waist in centimetres. Women also enter Hip.
  3. Measure the neck just below the larynx; men measure the waist at the navel and women at its narrowest point, and hips at their widest.
  4. Read the Body fat percentage.

How it works

Men: 495 ÷ (1.0324 − 0.19077 × log10(waist − neck) + 0.15456 × log10(height)) − 450. Women: 495 ÷ (1.29579 − 0.35004 × log10(waist + hip − neck) + 0.221 × log10(height)) − 450. All measurements are in centimetres. Impossible inputs, such as a neck larger than the waist, show a dash.

Example

A man 178 cm tall with a 38 cm neck and 85 cm waist comes out at 16.4%. A woman 165 cm tall with a 34 cm neck, 75 cm waist and 100 cm hips comes out at 28.9%.

Questions about Body Fat %

How accurate is the US Navy method?

Studies typically put it within about 3 to 4 percentage points of lab methods such as DEXA for most people. It is less reliable for very lean or very muscular builds.

Why does it not ask for my weight?

The method estimates fat from how the waist compares with the neck and height, not from weight. That also makes it useful for tracking change while your weight stays the same.

Use it from chat

You do not have to open Body Fat % to use it. Ask Xenition in plain language and it runs the right tool, then carries the answer into whatever you are working on — a document, a spreadsheet, a deck.

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