BMI Calculator
Calculate body mass index (BMI) from your height and weight in metric or imperial units and see the WHO category for adults.
About the BMI Calculator
Enter your weight and height to get your body mass index (BMI) and the World Health Organization (WHO) category it falls into. BMI is weight in kilograms divided by the square of height in metres. Metric mode takes kg and cm; imperial mode takes pounds plus feet and inches and applies the standard conversion factor, BMI = 703 × pounds ÷ inches². The result is rounded to one decimal place, and the category is decided from that rounded figure, so the number and the label always agree.
Example: 70 kg at 175 cm gives 70 ÷ (1.75 × 1.75) = 22.9, which is in the normal range. The WHO adult categories used here are underweight below 18.5, normal weight 18.5–24.9, overweight 25.0–29.9 and obese 30.0 and above. The coloured bar shows where your result sits on a scale from 10 to 45, with each band drawn to its true width, and the legend below highlights your category.
BMI is a quick screening measure for adults, not a diagnosis. It doesn't distinguish fat from muscle or show where fat is carried, so a muscular athlete can come out as overweight. It is not meant for children and teenagers, who are assessed with age- and sex-specific BMI charts, or for use during pregnancy. If your result worries you, talk to a doctor, who can look at other measures as well. If your height or weight is in other units, convert it first with the Unit Converter.
How to use the BMI Calculator
- 1
Choose units
Click Metric (kg/cm) or Imperial (lb/ft). Values you have already typed are not converted when you switch.
- 2
Enter your weight
Type your weight in kilograms or pounds.
- 3
Enter your height
Type your height in centimetres, or in feet and inches using the two boxes.
- 4
Read the result
Your BMI, its WHO category, the position on the coloured bar and the category legend appear as soon as both values are valid.
What it can do
Metric and imperial units
Kilograms and centimetres, or pounds with feet and inches.
WHO adult categories
Underweight, normal weight, overweight and obese, with the range for each shown in the legend.
Proportional scale
The coloured bar spans BMI 10 to 45 and each category takes up its real share, so the marker position is accurate.
Consistent rounding
The category is chosen from the same one-decimal value that is displayed, so 24.96 shows as 25.0 and is labelled overweight.
Limitations
- For adults only. It does not apply to children, teenagers or pregnant women.
- BMI doesn't account for muscle mass, body frame, age, sex or where fat is stored, so very muscular people and some older adults may be misclassified.
- Only the WHO international cut-offs are shown. Some Asian guidelines, including those used in India, set lower thresholds for overweight and obesity.
- It is a screening number, not medical advice or a diagnosis.
Privacy
Your height and weight are used only in your browser to calculate the result; they are not sent to FlexyPdf's servers or stored.
Frequently asked questions
What is a normal BMI for adults?
The WHO classes 18.5 to 24.9 as normal weight for adults. It is a population-level guide; for an individual, a doctor will also consider things like waist size, blood pressure and blood tests before drawing conclusions.
Can I use this calculator for my child?
No. For children and teenagers, the BMI number has to be compared with growth charts for their exact age and sex, which this tool does not include. Ask your paediatrician or use your country's official child BMI charts.
Are the BMI cut-offs different for Indians and other Asians?
Research has found that many Asian populations face higher health risks at a lower BMI, and some guidelines, including those used in India, therefore set lower thresholds for overweight and obesity. This calculator shows the WHO international categories only, so ask your doctor which cut-offs apply to you.
How is BMI calculated in pounds and inches?
Multiply weight in pounds by 703 and divide by height in inches squared. For 154 lb and 5 ft 9 in (69 inches): 703 × 154 ÷ (69 × 69) = 22.7.
Why might my BMI be misleading?
Muscle is denser than fat, so athletes and people who do heavy strength training can have a high BMI with little body fat. Older adults who have lost muscle can have a normal BMI with more body fat. That is why BMI is used for screening rather than diagnosis.
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