Calculate your Body Mass Index instantly. Supports metric and imperial units.
Enter your weight and height on the left to see your BMI result here.
A BMI between 18.5 and 24.9 is considered normal weight for most adults.
BMI is a useful screening tool but has limitations — it doesn't account for muscle mass, bone density, or body fat distribution. Always consult a doctor for medical advice.
BMI = weight(kg) ÷ height(m)². In imperial: BMI = (weight(lbs) ÷ height(in)²) × 703.
Get your BMI and category in seconds — metric, imperial, or mixed units. No sign-up.
Often not. Muscle weighs more than fat, so resistance-trained athletes commonly land in the overweight range despite low body-fat percentages. Pair BMI with a body composition test if you train heavily.
For most adults, 18.5 to 24.9 is classified as healthy. In adults over 65, slightly higher BMIs (up to about 27) are associated with the best longevity outcomes.
Whichever you're more comfortable measuring in. The numerical BMI is identical between the two — the conversion factor is built in.
Every few months is plenty if you're a healthy weight. If you're actively trying to gain or lose, weekly checks are sufficient — daily fluctuations are mostly water and digestion.
Yes. It doesn't distinguish muscle from fat, doesn't account for fat distribution (visceral vs subcutaneous), and varies in clinical meaning across ages and ethnicities. Treat it as one signal, not a verdict.
BMI is the most widely cited health metric in the world and the most-misunderstood. The ConvertDox BMI Calculator gives you the number quickly and — importantly — pairs it with the category and a clear interpretation, so you don't leave wondering what 24.7 actually means. The calculator supports both metric (kilograms and centimetres) and imperial (pounds and feet/inches) units, and you can mix and match if you happen to know your weight in kilos but your height in feet. The math is identical between the two: BMI = weight in kilograms divided by height in metres squared, with a 703 conversion factor when inputs are in pounds and inches. Because the calculation runs in your browser, your weight and height are never sent over the network — relevant if you'd rather not see your stats logged in a third-party analytics dashboard. The tool deliberately includes context around the result rather than just spitting a number: the category (underweight / normal / overweight / obese), what the category is generally taken to mean, and a reminder that BMI has known limitations for athletes, the elderly, pregnant women, and people of different ethnic backgrounds. For a deeper look at the formula and the alternatives, our companion BMI guide walks through everything in detail.
A BMI calculator works out your Body Mass Index — a number that estimates whether your weight is in a healthy range for your height. BMI is calculated by dividing your weight by the square of your height, and the result places you into categories: underweight, normal weight, overweight, or obese. It's a quick, widely-used screening tool that gives a general sense of whether weight may be affecting your health.
This calculator supports both metric (kilograms and centimetres) and imperial (pounds and feet/inches) units, and computes your BMI instantly in your browser — nothing is uploaded or stored. While BMI is a useful starting point, it's a general indicator rather than a complete picture of health: it doesn't distinguish muscle from fat, so very muscular people may read as 'overweight' despite low body fat. Use it as one signal among many, alongside guidance from a healthcare professional.
Get a quick snapshot of whether your weight sits in a generally healthy range for your height.
Use BMI as one reference point when planning weight-loss, maintenance, or muscle-gain goals.
Recalculate periodically to see how your BMI shifts as your weight changes over time.
Know your BMI before an appointment so you can discuss it knowledgeably with your physician.
Some health forms and insurance applications ask for BMI — calculate it quickly when needed.
Check BMI for yourself and family members to stay generally informed about healthy weight ranges.
BMI equals your weight in kilograms divided by the square of your height in metres (kg/m²). The imperial formula multiplies the pounds-over-inches-squared result by 703. This tool does the math for you in either unit system.
For most adults, a BMI between 18.5 and 24.9 is considered the normal range. Below 18.5 is underweight, 25 to 29.9 is overweight, and 30 or above is classed as obese.
BMI is a useful general screen but has limits. It doesn't distinguish muscle from fat, so athletes may read high, and it doesn't account for age, sex, or fat distribution. Treat it as one indicator, not the whole story.
No. The calculation happens entirely in your browser. Your height and weight are never uploaded, stored, or shared.
Adult BMI categories don't apply to children and teens, who are assessed using age- and sex-specific percentile charts. Consult a paediatrician for young people.
Yes, completely free with no signup and no limits on how often you can use it.