Health
Estimated body-fat percentage from BMI, age, and sex, using a population equation — not a direct body-composition measurement.
Results update as you type. No calculate button. All calculations run locally in your browser.
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| Measure | Value |
|---|---|
| BMI (input to the equation) | — |
| Estimated body fat | — |
| Implied fat mass | — |
| Implied lean mass | — |
| Other sex, same BMI and age | — |
Bars are scaled to the larger of the two values. The 10.8-point sex term is the only difference between the bars.
First BMI = weight (kg) ÷ height² (m²). Then estimated body fat % = 1.2 × BMI + 0.23 × age − 10.8 × sex variable − 5.4, where the sex variable is 1 for male and 0 for female. This is the Deurenberg equation.
Weight 65 kg, height 170 cm, age 30, female: BMI = 65 ÷ 1.70² = 22.5. Body fat % = 1.2 × 22.49 + 0.23 × 30 − 0 − 5.4 = 26.99 + 6.9 − 5.4 = 28.5%. Implied fat mass is 65 × 0.285 = 18.5 kg and implied lean mass is 46.5 kg. With the male sex term the same inputs give 17.7%. Use Reset example above to reproduce this result.
This is not a direct body-composition measurement: no skinfold, scan, or weighing method is involved, and the equation only recombines BMI, age, and sex. It can be inaccurate for athletes, older adults, and many body types, because two people with the same BMI and age can carry very different amounts of muscle and fat. The fat-mass and lean-mass figures are just the percentage applied to the entered weight, not separately measured quantities.
No. A scan or skinfold test measures the body directly; this page only applies a population equation to BMI, age, and sex.
The equation subtracts 10.8 points for men, reflecting average differences in the population it was fitted to. It is a group adjustment, not a measurement of the individual.
Because BMI cannot tell muscle from fat. A muscular person can have a high BMI — and therefore a high estimated body fat — while carrying little fat.
They are the estimated percentage applied to your entered weight (fat mass = weight × percentage; lean mass = the rest). They are not separately measured.
No. This calculation runs locally in your browser and the values you enter are not sent to a CalcMintly database.
No. The equation is an adult population formula and is not validated for children.
Results are estimates only and do not constitute professional or medical advice.