BMI Calculator – Work Out Your Body Mass Index
22.5
Normal weight (18.5 – 24.9)
BMI is a general screening measure and does not account for muscle mass, bone density, or body composition. It is not a diagnosis — consult a healthcare professional for personalized advice.
About BMI Calculator
Enter your height and weight in either metric or imperial units and see your Body Mass Index immediately, along with the category it falls into on a visual scale.
Body Mass Index is your weight divided by the square of your height. It is a rough screening figure used to sort adults into broad weight categories, and it is popular because it needs only two easily measured numbers.
It is worth knowing what BMI cannot tell you. It does not distinguish muscle from fat, so a very muscular person can register as overweight while carrying little fat. It does not account for where fat is stored, which matters medically. And the standard thresholds were derived largely from European populations — several health bodies use lower cut-offs for people of South Asian descent. Treat the number as a starting point for a conversation with a doctor, not a diagnosis.
What you can use it for
- Check where your current height and weight place you on the standard BMI scale.
- Convert between metric and imperial without doing the arithmetic yourself.
- Track the effect of a change in weight on the figure over time.
- Work out the weight range that corresponds to a given BMI band for your height.
- Prepare a figure to discuss at a medical appointment.
How it works, step by step
- 1
Choose your units
Switch between metric (centimetres and kilograms) and imperial (feet, inches and pounds).
- 2
Enter your height
Type your height in the selected units.
- 3
Enter your weight
Type your weight. The result updates as you type.
- 4
Read your BMI and category
The value appears with its category and a gauge showing where it sits on the scale.
Frequently asked questions
How is BMI calculated?
Weight in kilograms divided by height in metres squared. For imperial units, weight in pounds divided by height in inches squared, multiplied by 703. This calculator handles either.
What are the standard BMI categories?
For adults, the widely used ranges are: under 18.5 underweight, 18.5 to 24.9 healthy weight, 25 to 29.9 overweight, and 30 or above obese. Some health authorities apply lower thresholds for people of South Asian and other ancestries.
Is BMI accurate?
It is a screening tool, not a measure of health. It cannot tell muscle from fat, ignores where fat is carried, and does not account for age or build. Athletes in particular are often misclassified.
Does BMI work for children?
Not in this form. Children and teenagers are assessed against age-and-sex percentile charts rather than the fixed adult thresholds, so this calculator is intended for adults.
Is my health information sent anywhere?
No. The calculation runs entirely in your browser. Your height and weight are never uploaded, stored or logged.