BMI Calculator

How to use

Enter your height and weight and the BMI and healthy weight range appear instantly, with no submit button. You can switch between metric and imperial units, so if your latest check-up reported your weight in pounds you can type it straight in. Switching units converts the values you have already entered.

There are two common moments to reach for this. One is double-checking the BMI printed on a health check-up or insurance form, to confirm the number adds up. The other is the start of a diet or strength program, when you want to fix your current position and the gap to a healthy weight before you begin. It works best as the numeric starting point for a plan, not just a general health reading.

How it is calculated

BMI is weight in kilograms divided by height in metres squared (weight / height / height). The healthy weight range is the span that corresponds to a BMI of 18.5 up to 25. The "ideal weight" figure uses a BMI of 22, the value statistically associated with the lowest disease risk, as height (m) x height (m) x 22.

One thing worth knowing: the same BMI can be labelled differently around the world. A BMI of 27, for example, is "Overweight" under the WHO/CDC chart, not obesity. Many Asian health bodies set lower cut-offs, because at the same BMI Asian populations tend to carry more body fat and face higher risk of conditions like type 2 diabetes; the WHO has published additional Asian reference points at 23 and 27.5. If you are comparing figures from different countries, check which chart they are based on.

You may also see informal terms like "beauty weight" or "model weight" aiming at a BMI of 20 or below. These are not medically defined categories. This tool reports only the BMI 22 ideal weight, because that is the one figure with epidemiological backing as the point of lowest disease risk. Being underweight carries its own risks, so treat those lower targets with caution.

• WHO – Obesity and overweight (BMI definition & adult cut-offs)
• CDC – Adult BMI Categories (healthy weight range)
• WHO European Health Information Gateway – BMI cut-offs
• NIST Special Publication 811 (unit conversions)

FAQ

Why is my BMI high even though I am muscular?

BMI uses only height and weight and cannot tell whether that weight is muscle or fat. Muscle is denser than fat, so athletes with low body fat can still show a high BMI without being overweight. Treat BMI as a rough screen that does not measure body composition.

Can I use this for a child's BMI?

No. This tool is for adults aged 18 and over. Children's healthy ranges change with age and sex, so they are assessed with age- and sex-specific percentile charts instead. Use a paediatric BMI-for-age chart for anyone under 18.

If my BMI is in the healthy range, am I fine?

Not necessarily. It is possible to have a normal BMI but a high body fat percentage, sometimes called normal weight obesity. Body fat percentage and waist circumference are separate measures, so check those too for a fuller picture of your health.

What is the difference between ideal weight and "beauty weight"?

Ideal weight here means the BMI 22 figure statistically linked to the lowest disease risk. "Beauty weight" or "model weight" are informal terms with no medical basis that point to lighter targets. This tool shows only the evidence-based BMI 22 ideal weight.