BMI Calculator
Work out your Body Mass Index (BMI) from your height and weight, and see which weight category it falls into.
How this calculator works
BMI is calculated by dividing weight by the square of height. It's a quick screening tool, not a diagnosis — it doesn't distinguish muscle from fat.
Imperial inputs are converted to metric automatically before calculating.
How to interpret your BMI
Under 18.5 is considered underweight, 18.5–24.9 is considered a healthy range, 25–29.9 is considered overweight, and 30 or above is considered obese, according to standard adult BMI categories used by major health organizations worldwide.
BMI doesn't account for muscle mass, bone density, or body composition, so athletes and very muscular people often score higher than their actual body fat would suggest.
A worked example
Take someone who is 5'7" (67 inches) and weighs 160 lbs. Using the imperial formula — weight in pounds divided by height in inches squared, multiplied by 703 — gives (160 ÷ 4489) × 703 ≈ 25.1, landing just into the 'overweight' category.
Frequently asked questions
Is BMI accurate for everyone?
BMI is a useful screening tool for most adults but can be misleading for athletes, older adults, and people with unusually high or low muscle mass. It doesn't measure body fat directly.
What is a healthy BMI range?
For most adults, a BMI between 18.5 and 24.9 is considered a healthy weight range.