BMI for women:
weight ÷ height² in metres

How do you calculate BMI for women?

To calculate BMI for women, divide weight in kilograms by height in metres squared. A woman who weighs 62 kg and is 165 cm tall has a BMI of 22.8. The formula is the same for every adult, whatever their sex.

The BMI calculator on this site asks for weight in kilograms and height in centimetres, then converts the height to metres for you. If you only know your height in feet and inches, convert it to centimetres first so the formula receives the units it expects.

The female BMI formula with a worked example

A second case: a woman of 158 cm who weighs 70 kg has a BMI of 70 ÷ (1.58 × 1.58) = 28.0. Note that a short height produces a high BMI faster, because the height is squared in the denominator.

BMI chart for women: what the result means

The World Health Organization uses these adult categories: below 18.5 is underweight, 18.5 to 24.9 is a normal range, 25 to 29.9 is overweight and 30 or more is obesity. They are the same for women and men aged 18 and over. Some guidelines for South Asian adults use lower cut-offs, so ask your doctor which applies to you.

Use the table backwards when you want a target: pick your height, read off the weight range and see where you sit. The same ranges are used in clinics and in school or workplace health checks.

Both ends of the table come from the same formula rearranged: weight = BMI × height in metres squared. For 165 cm, 18.5 × 2.7225 gives 50.4 kg and 24.9 × 2.7225 gives 67.8 kg. Remember that the range is wide on purpose, about 17 kg at this height, because healthy bodies differ in frame size and muscle.

What BMI cannot tell women

BMI uses only weight and height. It cannot tell muscle from fat, where fat is stored, or how fit you are. Women typically carry a higher share of body fat than men at the same BMI, and the number shifts with age, so a result inside the normal range does not guarantee good health.

BMI is also not designed for use during pregnancy or for people under 18, who are assessed on growth charts. Treat the result as one screening figure and pair it with waist measurement, blood tests and advice from a clinician. Results here are estimates, not medical advice.

Common mistakes when working out your BMI

• Entering height in centimetres where metres are expected. 165 squared is 27,225, which gives a meaningless BMI near 0.002.
• Using pounds or stones without converting. Divide pounds by 2.2046 to get kilograms first.
• Squaring the wrong thing: you square the height, not the weight.
• Rounding the height early. 1.65 m is not 1.7 m, and that change alone moves a result by about one point.
• Treating 25 as a hard line. A BMI of 24.9 and one of 25.1 describe almost the same body.