Find body fat percentage for women, from BMI and age.
The Deurenberg equation, using the female-specific constant.
Women: 1.2 × BMI + 0.23 × age − 5.4
For women, the Deurenberg equation estimates body fat percentage as 1.2 × BMI + 0.23 × age − 5.4. This calculator applies it to your BMI and age and returns a single percentage.
Women naturally carry more essential fat than men, in breast tissue, hips and thighs, and for reproductive health. So a healthy body fat range for women sits several points higher than for men, and the formula's smaller subtracted constant builds this in. At the same BMI and age, the women's estimate is 10.8 points higher.
The estimate is useful for a quick screening, for understanding where you stand beyond the BMI number, and for tracking a fitness programme over months. It is not a direct measurement.
1. Calculate BMI = weight in kg ÷ (height in m)².
2. Multiply BMI by 1.2.
3. Multiply your age by 0.23.
4. Add these and subtract 5.4: body fat % = 1.2 × BMI + 0.23 × age − 5.4.
5. Clamp negative results to 0.
6. To see kilograms of fat, multiply your weight by the percentage and divide by 100.
Deurenberg's adult equation has one sex term, −10.8 × sex, with sex = 1 for men and 0 for women, plus a shared constant of −5.4. For women the sex term vanishes, leaving −5.4. The reference data came from hydrodensitometry, where body density from underwater weighing is converted to fat percentage using the Siri equation. That conversion assumes fixed densities for fat and fat-free tissue, which is itself an approximation. The equation explained most of the variation in the study group, with a prediction error of roughly 4 percentage points.
Body composition changes through a woman's life in ways a two-input formula cannot follow closely. Pregnancy adds fluid and tissue, so the equation should not be used then. After menopause many women gain abdominal fat and lose some muscle even if weight is stable, which the 0.23 × age term only partly captures. Regular strength training works the other way. A woman who lifts weights may be several points leaner than the formula predicts at her BMI.
Bioelectrical impedance scales, now common in Indian gyms, estimate body fat from how easily a small current passes through the body, and they are sensitive to hydration and the time of day. Skinfold callipers depend on the skill of the person measuring. DEXA is more accurate but expensive. Each method has its own bias, so readings from different methods should not be compared as if they were the same scale. Choose one method and repeat it under similar conditions to track change.
Ananya, a 27-year-old architect in Bengaluru who swims twice a week, has a BMI of 22.8. She wants a rough body-fat estimate to compare with her gym's scale reading.
Answer: Estimated body fat 28.2%
Judging the women's result against men's body-fat ranges, which are several points lower.
Using the formula during pregnancy or soon after childbirth.
Expecting it to match a bioimpedance scale reading exactly; different methods disagree by several points.
Checking daily; body fat changes slowly and the formula's error swamps day-to-day movement.
Quick body-composition estimate from BMI when no equipment is available.
Tracking the trend during a fitness or weight-loss programme.
Health camps and college fitness assessments screening many people quickly.
Estimating lean mass for use in a macro or calorie plan.
Why does the formula give a higher estimate for women at the same BMI?
On average, women naturally carry a higher body fat percentage than men at the same BMI, because of differences in body shape. The formula's smaller subtracted number for women reflects this.