BMI Calculator

One number, held in context.

Enter your height and weight for your Body Mass Index and what the range typically means.

How it works

Body Mass Index is your weight in kilograms divided by your height in meters squared. The result is placed in the standard WHO adult ranges: underweight (below 18.5), normal (18.5–24.9), overweight (25–29.9) and obese (30 and above).

When it helps

BMI is a quick screening number that's widely used, for example in health forms or as a rough starting point for fitness goals.

A worked example

For someone 175 cm tall weighing 68 kg: 1.75 m squared is 3.0625, and 68 ÷ 3.0625 = 22.2. That falls in the 18.5–24.9 'normal' range. The tool also turns the range around to show the weight band that matches it for your height — here roughly 56.7 kg to 76.3 kg.

If you use imperial units, the tool converts feet, inches and pounds to centimetres and kilograms first, so the result is identical to the metric calculation.

What BMI does and doesn't tell you

BMI is popular because it needs only two measurements and works well for spotting trends across large groups of people. For an individual it's a rough screen. It doesn't separate muscle from fat, so muscular people can show as 'overweight', and it says nothing about where fat is stored — waist size is often a better signal of health risk. Body shape, age, sex and ethnicity can also shift what a healthy BMI looks like.

If your result surprises you, consider it alongside other measures such as waist circumference or the Body Fat Calculator on this site, and talk to a doctor before making major changes.

Frequently asked questions

Is BMI accurate for everyone?

No. It doesn't distinguish muscle from fat, so athletes, older adults and children may get misleading results. Talk to a doctor for a real assessment.

Can children use it?

Children and teens need age- and sex-specific percentile charts, which this adult calculator doesn't use.

Are the categories the same everywhere?

The tool uses the WHO adult cut-offs. Some health bodies recommend lower thresholds for certain populations, for example people of Asian descent, where health risks start at lower BMI values.

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