BMI Calculator for Women

For adults aged 20 and over, adult BMI uses the same formula and cut-offs for women as for men, but a woman’s health picture also depends on body fat, where that fat sits and, for many, pregnancy plans. Alongside your BMI and healthy weight range, this calculator estimates body fat from BMI and age, checks your waist against the NIH threshold for women and shows the recommended pregnancy weight gain for your BMI.

How to use this tool

1. Enter your age, then your height and weight in US or metric units.
2. Optionally measure your waist just above the hip bones and enter it.
3. Read your BMI, category and healthy weight range for your height.
4. Check the body fat estimate, waist results and pregnancy weight-gain guide.

Formula

BMI = kg ÷ m²; estimated body fat % = 1.2 × BMI + 0.23 × age − 5.4; waist-to-height ratio = waist ÷ height

The body fat equation is Deurenberg’s (1991) adult formula with the female sex term; it is a population estimate, not a measurement. A waist over 35 in (88.9 cm) raises the risk of heart disease and type 2 diabetes for women (NIH). Pregnancy guidance follows the IOM ranges for one baby: underweight 28–40 lb, healthy 25–35 lb, overweight 15–25 lb, obesity 11–20 lb. Classification uses the unrounded BMI; displayed boundary weights are rounded. The body-fat estimate is withheld outside the study BMI range of 13.9–40.9 or above age 83. Its 4.1-point standard error is not a personal accuracy guarantee.

Example

A 35-year-old woman who is 5 ft 4 in (162.6 cm) and 145 lb (65.8 kg) has a BMI of 65.77 ÷ 1.6256² = 24.9, at the top of the healthy range (107.8 to under 145.6 lb for her height). Her estimated body fat is 1.2 × 24.9 + 0.23 × 35 − 5.4 ≈ 33%. With a 34 in waist her waist-to-height ratio is 34 ÷ 64 = 0.53, and the pregnancy guide for her BMI is 25–35 lb.