How to Calculate BMI
Calculate your Body Mass Index using metric or imperial units
⚡Quick Answer
Metric: weight(kg) ÷ height(m)². Imperial: weight(lbs) × 703 ÷ height(inches)². Under 18.5 = underweight, 18.5–24.9 = normal, 25–29.9 = overweight, 30+ = obese. Consult a doctor for health advice.
Step-by-Step Guide
Use the Metric Formula
Divide your weight in kilograms by your height in meters squared (BMI = kg ÷ m²).
Use the Imperial Formula
Multiply your weight in pounds by 703, then divide by your height in inches squared (BMI = lbs × 703 ÷ in²).
Interpret Your Result
Under 18.5 = underweight, 18.5–24.9 = normal weight, 25–29.9 = overweight, 30+ = obese.
Understand the Limitations
BMI does not account for muscle mass, age, or gender, so athletes and elderly people may get misleading results.
Frequently Asked Questions
Is BMI accurate for everyone?
No — BMI is a rough screening tool and is less accurate for athletes, the elderly, and pregnant women.
What is a healthy BMI range?
For most adults, a BMI between 18.5 and 24.9 is considered healthy.
Can I calculate BMI for children?
Children use age- and sex-specific BMI percentile charts instead of the standard adult ranges.