BMI calculator
Enter your height and weight to get your body mass index and the healthy weight range for your height. For adults 18 and over.
The formula
BMI = weight (kg) ÷ height (m)²Worked example
Someone 175 cm tall weighing 75 kg: 75 ÷ (1.75 × 1.75) = 75 ÷ 3.0625 = 24.5, which is in the healthy range. For 175 cm, that range is about 56.7 kg to 76.3 kg.
Categories follow the World Health Organization adult cut-offs, as used by healthdirect (checked 4 Nov 2026). This isn't medical advice.
Common questions
What is a healthy BMI?
For adults, 18.5 to 24.9 is generally considered a healthy weight range. 25 to 29.9 is overweight, and 30 or more is obese.
Is BMI accurate?
It's a quick screening tool, not a diagnosis. It doesn't tell muscle from fat, so athletes can score high. It also doesn't show where fat sits. Waist measurement adds useful information.
Does BMI work the same for everyone?
Not exactly. Some groups, including people of Asian background, can have higher health risks at a lower BMI, while for older adults a slightly higher BMI may be fine. Ask your GP what's right for you.
Can children use this?
No. Children and teenagers need age- and sex-specific BMI charts, so talk to your GP or child health nurse.