BMI Calculator
Calculate your Body Mass Index from height and weight and see where it falls on the standard ranges.
How it works
BMI = weight(kg) ÷ height(m)²
Weight in kilograms divided by height in meters squared. The standard adult ranges: under 18.5 underweight, 18.5–24.9 normal, 25–29.9 overweight, 30+ obesity. US units are converted first (1 lb = 0.4536 kg, 1 in = 2.54 cm).
Worked example
At 5′8″ (1.727 m) and 165 lb (74.8 kg): BMI = 74.8 ÷ 1.727² = 25.1 — just over the normal-range line.
Sources: WHO — BMI classification
Frequently asked questions
Is BMI accurate for athletes?
Not very. Muscle is denser than fat, so muscular people often read "overweight" while carrying little fat. Waist measurement and body-fat percentage tell more for athletic builds.
Do the same ranges apply to children?
No — children and teens use age- and sex-specific percentile charts, not the fixed adult cutoffs.
What BMI should I aim for?
For most adults 18.5–24.9 is the statistical "normal" band, but the healthiest weight for you depends on body composition, age and health markers — discuss targets with your doctor.
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This is a general educational estimate, not medical advice. Bodies differ — for decisions about diet, training, medication or health conditions, talk to a doctor or registered dietitian.