Body Mass Index (BMI) is a quick screening number that relates your weight to your height. It places you in one of four categories: underweight, normal weight, overweight, or obese, and it is the starting point most health guidelines use.
Enter your weight and height below. The calculator shows your BMI, marks it on the color scale, and tells you the healthy weight range for your height. Switch between metric and imperial units at any time.
BMI Calculator
Check your Body Mass Index and see which category you fall into.
How the math works
Metric: BMI = weight(kg) divided by height(m) squared. Example: 75 kg at 1.80 m gives 75 / (1.8 x 1.8) = 23.1.
Imperial: BMI = 703 x weight(lbs) divided by height(in) squared.
Categories (WHO): under 18.5 underweight, 18.5-24.9 normal weight, 25-29.9 overweight, 30 and above obese.
Frequently Asked Questions
What is a healthy BMI?
For most adults, a BMI between 18.5 and 24.9 is considered the healthy range. Below 18.5 is underweight, 25 to 29.9 is overweight, and 30 or above is classified as obese.
Is BMI accurate?
BMI is a useful screening tool, but it is not a diagnosis. It cannot tell muscle from fat, so muscular athletes can score as overweight while being lean, and older adults can have a normal BMI with too little muscle. Use it together with waist measurement and how you feel and perform.
How is BMI calculated?
Divide your weight in kilograms by your height in meters squared. For example, 75 kg at 1.80 m gives 75 / (1.8 x 1.8) = 23.1. In imperial units, multiply weight in pounds by 703 and divide by height in inches squared.
My BMI is high. What should I do?
Treat it as a nudge, not a verdict. Start with small sustainable changes: a modest calorie deficit, more daily steps, and strength training twice a week. Our calorie deficit calculator and macro calculator can turn that into exact daily targets. If you have health concerns, talk to your doctor.