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Estimating body fat from BMI
The Deurenberg formula, published in 1991, uses your BMI, age and sex:1
Body fat % = 1.2 × BMI + 0.23 × age − 10.8 × sex − 5.4 (sex = 1 for men, 0 for women)
| Example | Estimate |
|---|---|
| Man, 40, BMI 24 | 1.2 × 24 + 0.23 × 40 − 10.8 − 5.4 = 21.8% |
| Woman, 40, BMI 24 | 1.2 × 24 + 0.23 × 40 − 5.4 = 32.6% |
It's an estimate for groups, so it can be off for individuals, especially muscular people.
General body fat ranges
The American Council on Exercise gives these general ranges:2
| Women | Men | |
|---|---|---|
| Essential fat | 10–13% | 2–5% |
| Athletes | 14–20% | 6–13% |
| Fitness | 21–24% | 14–17% |
| Average | 25–31% | 18–24% |
| Obese | 32% and above | 25% and above |
Ways to measure body fat
| Method | Accuracy | Notes |
|---|---|---|
| DEXA scan | High | Also measures bone; costs money |
| Underwater weighing / air displacement (Bod Pod) | High | Found in research and some gyms |
| Skinfold calipers | Moderate | Depends on the skill of the person measuring |
| Smart scales (bioelectrical impedance) | Low to moderate | Affected by hydration; best for trends |
| Formulas (Deurenberg, RFM) | Low to moderate | Free; good for a rough idea |
| What body fat percentage shows | What it doesn't show |
|---|---|
| How much of your weight is fat | Where on your body the fat is stored |
| Fat separately from muscle | An exact figure, unless measured with equipment like DEXA |
| Changes in fat even when your weight stays the same | Reliable day-to-day changes from smart scales, which shift with hydration |
Frequently asked questions
Is body fat percentage better than BMI?
It's more direct, because it measures fat rather than weight. But accurate measurement needs equipment, while BMI needs only a scale and a tape measure. BMI vs. other measures.
Why do women have more body fat at the same BMI?
Women naturally carry more essential fat, linked with reproductive health.2 That's why body fat ranges differ by sex while BMI categories don't.
Sources
Kept up to dateLast updated October 9, 2026
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This page is for education and is not medical advice. Talk with a healthcare professional about your weight and health.
