BMI Calculator
Body Mass Index from weight and height.
How to use
- 1 Enter your weight in kilograms.
- 2 Enter your height in centimetres.
- 3 Read your BMI, rounded to one decimal place.
- 4 Check the weight category shown alongside it.
About BMI Calculator
The BMI Calculator works out your Body Mass Index from your weight in kilograms and your height in centimetres.
BMI is defined as weight divided by height squared in metres, and this tool does the conversion and the maths for you, rounding the result to one decimal place and labelling it with the standard World Health Organization category.
BMI is a quick, widely used screening number.
Below 18.5 is classed as underweight, 18.5 to 24.9 as normal weight, 25 to 29.9 as overweight, and 30 or above as obese.
It is a useful first indicator and an easy way to track changes over time, though it is worth remembering its limits: BMI does not distinguish muscle from fat and was never designed to diagnose an individual, so very muscular or very tall people can sit outside the "normal" band while being perfectly healthy.
Treat the figure as a starting point for a conversation with a clinician, not a verdict.
Enter your weight and height and the result appears immediately, with the category shown as a clear badge.
The calculation runs entirely in your browser — your measurements are never uploaded or stored — and it works offline.
It is the fastest way to get a reliable BMI figure without handing your personal data to a website.
FAQ
What are the BMI categories?
Under 18.5 is underweight, 18.5–24.9 is normal, 25–29.9 is overweight, and 30 or above is obese.
Is BMI accurate for everyone?
It is a general screening tool and does not account for muscle mass, body composition or age, so it can misclassify athletes and others. Use it as a guide, not a diagnosis.
Is my data sent anywhere?
No. The calculation happens entirely in your browser and nothing is uploaded or stored.