BMI calculator
Calculate your Body Mass Index (BMI) from your height and weight, in metric or imperial units.
Fill in the fields and press Calculate to see your result here.
How this calculation works
BMI is weight divided by height squared. In metric units it is kg ÷ m²; in imperial units it is 703 × lb ÷ in², where 703 converts pounds and inches into the same kg/m² scale. The standard World Health Organization categories are: under 18.5 underweight, 18.5–24.9 normal, 25–29.9 overweight, and 30 or above obese.
Health note: BMI is a general screening figure and is not a medical diagnosis. Talk to a doctor or other qualified health professional about your weight and health.
Tips
BMI is a screening tool, not a diagnosis
It doesn't distinguish muscle from fat, so very muscular people can show a higher BMI without excess body fat.
Double-check your units
Mixing centimetres with pounds, or feet with kilograms, is the most common cause of an unrealistic BMI result.
Waist size adds context
BMI ignores where weight is carried. Waist circumference and overall fitness give extra information that a single ratio cannot.
Some organisations use different cut-offs
Certain health bodies suggest lower thresholds for some populations, so the standard categories are a general guide rather than a personal verdict.
Trends matter more than one reading
Small day-to-day changes in weight are normal. If you track BMI, look at the direction over weeks rather than a single number.
Frequently asked questions
Is BMI accurate for everyone?
It's a useful general screening measure but is less reliable for athletes, older adults, and during pregnancy. For a full health assessment, talk to a doctor.
What's a healthy BMI range?
18.5 to 24.9 is classed as the normal range for most adults, though healthy weight can vary by individual.
Is this medical advice?
No. This calculator gives general information only and isn't a substitute for advice from a qualified healthcare professional.