BMI Calculator
Underweight | Normal | Overweight | Obese
This free BMI Calculator tells you your Body Mass Index in seconds. BMI is a simple number worked out from your height and weight, and doctors, schools, gyms, and health organisations around the world use it as a first quick check of whether an adult is underweight, in the normal range, overweight, or obese. It is not a complete health report, but it is a helpful starting point for understanding your body and deciding whether you may want to talk to a health professional.
The calculator supports both measurement systems. If you know your weight in kilograms and your height in centimetres, use the metric option. If you think in pounds, feet, and inches, switch to imperial and the tool converts everything for you automatically. Along with your BMI score to one decimal place, you will see your category highlighted in colour and the healthy weight range for your exact height, so you can see how close you are to that range. All calculations happen locally in your browser. Your height and weight are never uploaded, saved, or shared with anyone.
How to use
- Choose your units: Metric if you use kilograms and centimetres, or Imperial for pounds and feet.
- Type your current weight carefully in the weight box provided.
- Type your height, using centimetres for metric, or feet and inches for imperial.
- Click Calculate BMI to see your score, your category, and your healthy range.
- Change a value and calculate again if you want to test a different weight.
Frequently asked questions
What is a healthy BMI?
For most adults, a BMI between 18.5 and 24.9 is classed as the normal or healthy range. Below 18.5 is underweight, 25 to 29.9 is overweight, and 30 or above is obese. These ranges are general guides, not personal medical advice.
Is BMI accurate for everyone?
BMI does not measure body fat directly. Very muscular people, athletes, pregnant women, older adults, and children can get misleading results, because muscle weighs more than fat and growing bodies change quickly. Treat the result as a guide only.
Should I worry if my BMI is outside the normal range?
A single BMI result is not a diagnosis. If your result concerns you, the sensible next step is to speak with a doctor or qualified health professional, who can consider your full health, lifestyle, and medical history.
Is my data private?
Yes. This calculator runs entirely in your browser. The numbers you enter are not sent to any server and are gone as soon as you close the page.
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