BMI Calculator
Calculate your Body Mass Index (BMI) instantly. Enter your height and weight below to see which weight category you fall into.
What is BMI?
Body Mass Index (BMI) is a simple measure that uses your height and weight to estimate whether you are a healthy weight. It is widely used by health organisations as a quick screening tool, though it does not distinguish between fat and muscle mass.
The BMI formula
BMI is calculated as weight in kilograms divided by height in metres squared:
For example, someone who is 175 cm tall and weighs 70 kg has a BMI of 70 ÷ 1.75² ≈ 22.9 — a normal, healthy weight.
BMI categories (adults)
| BMI range | Category |
|---|---|
| Under 18.5 | Underweight |
| 18.5 – 24.9 | Normal weight |
| 25.0 – 29.9 | Overweight |
| 30.0 – 34.9 | Obesity class I |
| 35.0 – 39.9 | Obesity class II |
| 40.0 and above | Obesity class III |
Frequently asked questions
How do I calculate my BMI?
BMI = weight (kg) ÷ height (m)². Enter your height in cm and weight in kg above and the calculator does the rest.
What is a healthy BMI range?
A BMI between 18.5 and 24.9 is generally considered a healthy weight for most adults.
Is BMI accurate for everyone?
BMI is a useful screening tool but does not account for muscle mass, bone density or body composition. Athletes and older adults may get misleading results.
What BMI should a child use?
Children and teens use age- and sex-specific percentile charts, not the adult BMI ranges shown here.
Note: BMI is a screening tool and not a diagnosis of body fatness or health. Always consult a healthcare professional for personal advice.