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How the calculation works
Here is the exact math behind your result, using your own numbers.
In pounds: a worked example
- Height in inches: 5 ft 5 in = 5 × 12 + 5 = 65 in.
- Square it: 65 × 65 = 4,225.
- Multiply weight by 703: 140 × 703 = 98,420.
- Divide: 98,420 ÷ 4,225 = 23.29, which rounds to 23.3.
What's different for women
The formula doesn't change, but the same BMI can mean something different:
- More body fat at the same BMI. On average, women carry more body fat than men with the same BMI. That's normal, and the categories already allow for it in a broad way.
- Where fat is stored matters. Fat around the waist is more closely linked with heart disease and type 2 diabetes than fat on the hips and thighs. A waist over 35 inches (88 cm) is linked with higher risk for women, even at a healthy BMI.1
- Life stages change the picture. BMI isn't used during pregnancy; pre-pregnancy BMI sets weight-gain goals instead. After menopause, fat tends to shift toward the waist, so waist size becomes more useful alongside BMI.
Check your waist and estimated body fat
Relative fat mass (RFM) estimates body fat from just your height and waist. It was developed in 2018 as a simple alternative to BMI, and it doesn't need a scale.2
Measure your waist at the belly button, standing, after breathing out normally.
Frequently asked questions
Is there a different BMI chart for women?
No. Adult women and men use the same BMI chart and categories.3 Only children and teens have separate charts for girls and boys.
What is a healthy BMI for a woman?
18.5 to 24.9 for adults aged 20 and over.3 Some guidelines use lower cutoffs for women of Asian descent: Asian BMI.
How do I calculate BMI for women in pounds?
Multiply your weight in pounds by 703, then divide by your height in inches squared. The calculator above does this for you and shows each step.
Does BMI work for older women?
The same categories apply, but height loss and muscle loss with age can affect the result. BMI for older adults.
Sources
This page is for education and is not medical advice. Talk with a healthcare professional about your weight and health.
