BMI Calculator

Body mass index is a quick screening measure that relates weight to height. It is used by doctors, insurers and health services worldwide as a first indication of whether weight might affect health. This calculator works in kilograms and centimetres or pounds, feet and inches, and shows your category, the healthy weight range for your height and BMI Prime.

Common uses

• Check your BMI as part of a general health review.
• Track changes over time during a fitness or weight plan.
• Find a healthy target weight range for your height.
• Compare metric and imperial measurements easily.

Tips for best results

• Measure height without shoes and weight at the same time of day for consistency.
• Use the Asian cut-offs if you are of Asian descent; risk rises at lower BMI.
• Do not use adult BMI categories for children and teenagers – they need age- and sex-specific charts.
• Treat BMI as a starting point and talk to a health professional for advice.

The formula

BMI equals weight in kilograms divided by height in metres squared. For imperial units, the calculator converts pounds to kilograms (× 0.4536) and inches to centimetres (× 2.54) first. For example, 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) = 22.9. BMI Prime is your BMI divided by the upper limit of the normal range, so values above 1.0 indicate overweight.

Asian cut-off points

A WHO expert consultation found that people of Asian descent often have higher health risks at lower BMI values. Many countries in Asia therefore use 23 as the threshold for overweight and 27.5 for higher risk. Tick the option to apply these cut-offs. The calculator gives information only and is not medical advice; your data never leaves your device.