BMI Calculator
Work out your body mass index (BMI) from your height and weight. See which weight category you fall into and the healthy weight range for your height — in metric or imperial units.
How to use it
Enter your height and weight using whichever unit system you prefer — the calculator converts for you. It returns your BMI, the category it falls in, and the weight range that would put you in the healthy band for your height.
BMI is a quick screening number, not a diagnosis. It can’t tell muscle from fat, so very muscular people may read high, and it isn’t meant for children, pregnancy, or athletes. Treat it as a starting point and talk to a clinician about your individual health.
Frequently asked questions
How is BMI calculated?
BMI is your weight in kilograms divided by the square of your height in metres (kg/m²). In imperial units it's 703 × pounds ÷ inches². This calculator does the unit conversion for you.
What is a healthy BMI?
For most adults, 18.5–24.9 is considered a healthy weight, below 18.5 is underweight, 25–29.9 is overweight, and 30 or above is obesity. These bands are general guidance and don't apply to children.
Is BMI accurate for everyone?
BMI is a screening tool, not a diagnosis. It doesn't distinguish muscle from fat, so athletes can read high, and it isn't suitable for children, pregnancy, or some populations. Use it alongside other measures and professional advice.
BriskToolbox provides estimates for general information only and is not medical advice. Talk to a healthcare professional about your individual health.