BMI Calculator

Body mass index in metric or imperial, with your healthy range.

Your BMI
Healthy weight for your height
Distance from that range
Where you sit on the scale
BMI is a screening figure, not a diagnosis — it cannot tell muscle from fat, and thresholds differ by age and ethnicity. Talk to a doctor before acting on it.
How this works
Metric: BMI = weight (kg) ÷ height (m)² Imperial: BMI = 703 × weight (lb) ÷ height (in)²
WHO categoryBMI
UnderweightBelow 18.5
Healthy weight18.524.9
Overweight25.029.9
Obese class I30.034.9
Obese class II35.039.9
Obese class III40.0 and above
  • Measures mass, not body fat — muscular builds are misclassified.
  • South and East Asian populations: 23 commonly used as the overweight threshold.
  • Under 18s need age-and-sex percentile charts, not these categories.
What is a healthy BMI?

The WHO considers 18.5 to 24.9 healthy for most adults. Many health bodies lower the overweight threshold to 23 for people of South or East Asian descent.

Is BMI accurate for athletes?

No. BMI cannot distinguish muscle from fat, so muscular people are often classed as overweight despite low body fat. Waist measurement or body fat percentage is more useful for them.

Can I use this for my child?

No. Children and teenagers need BMI-for-age percentile charts specific to their age and sex — ask a paediatrician or use a CDC/WHO growth chart.

Keep going
Percentage Calculator Find a percentage of a number, or the percentage change between two numbers. Age Calculator Your exact age in years, months, days — plus your next birthday countdown. Unit Converter Length, weight, temperature, volume, area and speed in one tool.