Body Fat from BMI
Free Body Fat from BMI calculator with clear step-by-step results.
About Body Fat from BMI
The Deurenberg equation estimates body fat from BMI, age and sex.
Formula
Formula
Body fat % ≈ 1.2×BMI + 0.23×age − 10.8×sex − 5.4
Worked example
With the default values below, Body Fat from BMI returns Estimated Body Fat of 23.0%. Change any input above and every figure here is recalculated in your browser.
Inputs used
- BMIaccepts 10–60
- 26
- Age (years)accepts 1–120
- 35
- Sexaccepts 0–1
- 1
Results
- Estimated Body Fat
- 23.0%
- Body Fat Category
- Healthy range
- Approx. Lean Mass (%)
- 77.0%
Step by step
- 1Values used
- 2Formula
- 3Estimated Body Fat= 23.0
- 4Body Fat Category= Healthy range
- 5Approx. Lean Mass (%)= 77.0
Assumptions and limits
- The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to 1 decimal place, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
- Estimates are general guidance — consult a healthcare professional for personal medical advice.
- This is an estimate for general information and not professional medical advice. See the full disclaimer for the limits that apply to this kind of calculator.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Estimates are general guidance — consult a healthcare professional for personal medical advice.
Frequently Asked Questions
How does this calculator work?
The Deurenberg equation estimates body fat from BMI, age and sex.
Why does this matter?
A population estimate — accurate only on average.