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BMI Calculator — Body Mass Index & Healthy Weight
Calculate your Body Mass Index and find your healthy weight range — metric or imperial.
✓ Free✓ No Login✓ Metric & Imperial✓ Healthy Range✓ BMI Prime
BMI Categories Reference
Severely Underweight
0 – 16Underweight
16 – 18.5Healthy Weight
18.5 – 25Overweight
25 – 30Obese Class I
30 – 35Obese Class II
35 – 40Obese Class III
40 – 40+⚠️ BMI Limitations
!Does not measure body fat directly
!Overestimates fat in muscular people
!Underestimates fat in elderly people
!Does not account for fat distribution
!Different healthy ranges for children
🔧 Related Tools
📖 How to Use the BMI Calculator
1
Choose Your Units
Select Metric (kg and cm) or Imperial (pounds and feet/inches) — whichever you're most comfortable with.
2
Enter Height & Weight
Type in your current weight and height. Decimal values are supported for precise results. Imperial splits height into feet and inches.
3
Get Your Results
Click Calculate to see your BMI score, category, BMI Prime and healthy weight range. The gauge shows exactly where you sit on the full BMI scale.
❓ Frequently Asked Questions
Is the BMI calculation different for women and men?+
No — the standard adult BMI formula (weight divided by height squared, kg/m²) and the category ranges are identical for women and men. BMI does not account for differences in body composition, such as muscle versus fat, which is why it is a screening measure rather than a diagnosis.
How do I calculate BMI in kilograms?+
Switch the calculator to metric and enter your weight in kilograms and height in centimetres. The formula is weight ÷ height² using metres: for example, 70 kg at 175 cm is 70 ÷ 1.75² = 22.9 — inside the healthy range.
What is BMI Prime?+
BMI Prime is your BMI divided by 25 (the upper limit of healthy BMI). A value below 1.0 is in the healthy range, above 1.0 is overweight. It makes it easy to see how far from healthy your BMI is.
What is BMI?+
Body Mass Index (BMI) is a simple calculation using height and weight to estimate body fat levels. It's used as a screening tool to identify potential weight-related health issues.
What is a healthy BMI range?+
For most adults, a BMI between 18.5 and 24.9 is considered healthy. Below 18.5 is underweight, 25–29.9 is overweight, and 30 or above is considered obese.
Is BMI accurate?+
BMI is a useful general screening tool but has limitations. It doesn't account for muscle mass, bone density, age, sex or ethnicity. Athletes with high muscle mass may have a high BMI without excess fat.
How is BMI calculated?+
BMI = weight (kg) ÷ height (m)². In imperial units: BMI = (weight in lbs × 703) ÷ height in inches². Our tool handles both automatically.
What is the BMI Prime?+
BMI Prime is your BMI divided by 25 (the upper limit of healthy BMI). A value below 1 is healthy, above 1 is overweight. It makes it easy to see how far from healthy your BMI is.