BMI (body mass index) is a number calculated from your weight and height. It estimates whether you are in an underweight, healthy, overweight, or obese range. The formula is weight (kg) divided by height (m) squared, or weight (lb) × 703 divided by height (in) squared.

Is BMI accurate for women?

BMI is a general screening tool — not a perfect measure of health. It does not distinguish between muscle and fat, doesn't account for body composition, bone density, or where fat is stored. Many healthy, athletic, and pregnant or postpartum women fall outside the 'normal' range. Use BMI as one signal among many, alongside waist measurement, energy, strength and how your clothes fit.

What is a healthy BMI for women?

For most adult women, a BMI between 18.5 and 24.9 is considered the healthy range. 25–29.9 is classified as overweight, and 30 or above as obese. Below 18.5 is considered underweight. These ranges are the same for adult men and women.

How do I calculate BMI by hand?

Metric: divide your weight in kilograms by your height in meters squared. Example: 65 kg ÷ (1.65 m × 1.65 m) ≈ 23.9. Imperial: multiply weight in pounds by 703, then divide by your height in inches squared. Example: (140 × 703) ÷ (65 × 65) ≈ 23.3.

Does BMI work during pregnancy or postpartum?

No. BMI is not an appropriate measure during pregnancy or the early postpartum period. Talk with your healthcare provider about pregnancy weight gain targets and postpartum recovery instead.

What should I do if my BMI is outside the healthy range?

Use it as a prompt to talk with a qualified healthcare provider — not as a diagnosis. They can look at your full picture: body composition, blood work, lifestyle, cycle health, mental health and goals. Sustainable changes to nutrition, movement, sleep and stress matter far more than a single number.

BMI Calculator for Women — Body Mass Index Calculator

BMI Calculator for Women

Calculate your body mass index in metric or imperial units. See your BMI and what category it falls into — instantly and privately.

For information only — not medical advice

BMI is a general screening tool. It does not measure body composition or overall health. Speak to a qualified healthcare provider before making health decisions.

Calculate your BMI

Height (cm)

Weight (kg)

Tracking your menstrual cycle? Try our Luteal Phase Calculator.

Reference

BMI Categories

The World Health Organization's standard BMI categories for adults.

Underweight

Below 18.5

Healthy weight

18.5 – 24.9

Overweight

25.0 – 29.9

Obese

30.0 and above

How it works

How the Body Mass Index Calculator Works

BMI is calculated using a simple formula based on your height and weight.

Metric: BMI = weight (kg) ÷ height (m)².

Imperial: BMI = (weight in lb × 703) ÷ height (in)².

Your number is then matched to one of four standard categories — underweight, healthy, overweight, or obese.

Important

What BMI Doesn't Measure

Body composition — muscle vs fat vs bone
Where fat is stored on your body
Fitness level, strength, or cardiovascular health
Hormonal health or menstrual cycle status
Pregnancy, postpartum, or breastfeeding
Mental and emotional well-being

Treat BMI as one data point — not a verdict. A qualified healthcare provider can give you the full picture.

Also curious about your luteal phase?

BMI doesn't account for hormonal or cycle health. Pair this with the Luteal Phase Calculator to see how long your luteal phase typically runs and what's considered normal.

FAQs