About the bmi calculator
Body mass index (BMI) compares your weight with your height and is widely used to screen for weight categories that may affect health. This calculator uses the standard adult formula and the World Health Organization categories.
BMI is only a starting point. Athletes with a lot of muscle can have a high BMI at a healthy body fat level, and BMI can underestimate risk in older adults. For children and teens, BMI is interpreted using age and sex percentiles, which this tool does not provide.
Formula
BMI = weight (kg) ÷ height (m)². In US units: BMI = 703 × weight (lb) ÷ height (in)².
Frequently asked questions
What is a healthy BMI?
For adults, a BMI from 18.5 to 24.9 is considered the healthy weight range by the WHO and CDC.
Is BMI accurate for athletes?
Not always. BMI cannot tell muscle from fat, so very muscular people may be classed as overweight. Waist size and body fat percentage give extra context.
How do I lower my BMI?
Lasting changes in eating and activity help most. Use the calorie calculator to estimate your daily needs, and ask a health professional for personal advice.
These calculators give general estimates and are not medical advice. Talk to a doctor or registered dietitian before changing your diet or exercise routine.