Your Body Mass Index, in seconds
Metric or imperial, for adult men and women. Get your BMI, category, and the exact range for a healthy weight at your height.
Your details
Your BMI
Slightly elevated risk. Small habit changes can make a meaningful difference.
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How we calculate BMI
Body Mass Index is weight divided by the square of height. The formula has been used by clinicians for decades as a fast screen for weight status.
- Metric: BMI = weight (kg) ÷ height (m)²
- Imperial: BMI = weight (lb) × 703 ÷ height (in)²
- Healthy range: 18.5 – 24.9 for adults aged 20+
See the full BMI chart or BMI by age & gender.
What BMI does not tell you
BMI is useful, but it's blunt. It treats muscle and fat the same, and it doesn't know where your weight sits on your body. For a fuller picture, also check:
- Waist circumference — more closely tied to metabolic risk than BMI alone.
- Body-fat percentage — especially for athletes, where BMI overestimates fat.
- Trends over time — a single reading matters less than the direction you're moving in.
Frequently asked questions
What is a healthy BMI for adults?+
For adults, a BMI between 18.5 and 24.9 is considered healthy, 25 to 29.9 is overweight, and 30 or above is classified as obesity. These categories apply to most adults aged 20 and older.
How is BMI calculated?+
BMI equals your weight in kilograms divided by the square of your height in metres (kg/m²). In imperial units, BMI equals weight (lb) × 703 ÷ height (in)².
Is BMI accurate for everyone?+
BMI is a screening tool, not a diagnosis. It doesn't distinguish between muscle and fat, so athletes with high muscle mass can score as overweight. Pregnant people, children, and older adults need different scales.
What is a healthy BMI for women?+
The healthy BMI range of 18.5–24.9 is the same for adult men and women. However, body composition differs between sexes, which is why BMI is best interpreted alongside waist circumference and other measurements.
What is a healthy BMI for men over 40?+
Standard BMI targets still apply (18.5–24.9), but muscle mass declines with age, which can hide body-fat gain. Men over 40 should pair BMI with waist circumference (aim for under 40 in / 102 cm) for a clearer picture.