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BMI calculator
Enter your height and weight to see your body mass index, its class and the weight range that counts as normal for your height.
Your body mass index
This number is a statistical index for adults and does not replace a doctor’s advice.
This tool runs entirely inside your browser. No file or text is sent to any server.
How to use
- Write your height in centimetres and your weight in kilograms, for example 175 and 70.5. Persian digits are accepted too.
- As soon as both are filled in, the result appears: the index, its class and your place on the coloured bar.
- Under the bar you see the weight range that is normal for your height and, if your weight is outside it, how far outside.
Notes on this tool
BMI is weight in kilograms divided by height in metres squared. For 70 kg and 175 cm that is 70 ÷ (1.75 × 1.75), about 22.9.
The classes are the WHO classes for adults: under 18.5 underweight, 18.5 to 24.9 normal weight, 25 to 29.9 overweight, and from 30 obesity, split into three grades at 30, 35 and 40.
The index is shown with one decimal and the class is taken from that rounded number, so 24.96 becomes 25.0 and overweight, never a figure that disagrees with its class.
You may write the height in metres too, with a decimal point: 1.75 is 175 cm, and the tool says under the result how it read it. A number without a decimal point is always centimetres.
The normal weight range is the weights that give a BMI of 18.5 to 24.9 at your height.
BMI only compares weight with height; it does not see fat, muscle or where fat sits. It is not suited to children and teenagers (their classes depend on age and sex), to pregnant or breastfeeding women or to very muscular athletes, and for older people the tool may not give an exact result.
Frequently asked questions
What is body mass index (BMI)?
A simple number, weight divided by height squared, used to screen the weight of adults: it shows which class your weight falls in for your height. It is often shortened to BMI.
If my BMI is not in the normal range, does that mean something is wrong?
Not necessarily, and not from this number alone. BMI is a screening figure, not a diagnosis: waist size, blood pressure, blood sugar and cholesterol, and lifestyle matter too. For any decision about a diet or a change of weight, talk to a doctor or a dietitian.
Why does the result differ a little from other calculators?
The usual reasons are rounding and the classes. This tool uses the international WHO classes; for Asian populations the same organisation also suggested 23 and 27.5 as points for public health action, so some sources treat the risk as starting at a BMI of about 23.
Are the height and weight I enter saved or sent anywhere?
No. The calculation happens entirely in your browser; nothing is sent to a server and nothing is stored.
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