Calculate your Body Mass Index with metric or imperial units. See your BMI category, healthy weight range, and ideal weight instantly.
This BMI calculator works out your Body Mass Index from your height and weight, then shows which weight category you fall into and the healthy weight range for your height — instantly and entirely in your browser.
Body Mass Index is a simple ratio of weight to height (weight in kilograms divided by height in metres squared) that the World Health Organization uses to screen for underweight, healthy weight, overweight, and obesity in adults. It is not a perfect measure of health, but it is a quick, widely understood first check that needs nothing more than a tape measure and a set of scales. This tool accepts both metric and imperial units, updates the moment you type, and plots your result on a colour-coded scale so you can see at a glance where you sit. People use it to:
Everything is calculated on your device, so your height and weight are never uploaded or stored. Keep in mind that BMI is a screening tool, not a diagnosis: it does not distinguish muscle from fat, so very muscular people may read as overweight, and it is interpreted differently for children, older adults, and during pregnancy. Treat the result as a starting point for a conversation with a healthcare professional, not a verdict.
A BMI between 18.5 and 24.9 is considered normal weight for adults. Below 18.5 is underweight, 25 to 29.9 is overweight, and 30 or above is classified as obese by the WHO.
BMI equals your weight in kilograms divided by your height in metres squared (kg/m²). For imperial units the formula is weight in pounds divided by height in inches squared, multiplied by 703. This calculator handles the conversion for you in both unit systems.
BMI for children and teens aged 2 to 19 is interpreted differently — it is compared against age and sex-specific percentiles rather than fixed cutoffs. This calculator uses adult BMI thresholds, so it is not suitable for assessing children.
Not always. Muscle is denser than fat, so people with a lot of muscle — athletes, bodybuilders, heavy manual workers — can read as overweight or obese on BMI while carrying very little body fat. In those cases a body-fat measurement is a better guide.
The BMI formula and the standard adult categories are the same for men and women. Women naturally carry a higher proportion of body fat at the same BMI, so the number is best read alongside other measures like waist circumference rather than in isolation.
It is the weight range that keeps your BMI between 18.5 and 24.9 for your specific height. This tool shows that range automatically once you enter your height, in whichever unit system you have selected.
Yes. It is completely free with no sign-up, and every calculation runs locally in your browser. Your height and weight are never sent to a server or stored anywhere.