How the BMI calculator works
Body Mass Index (BMI) is your weight in kilograms divided by the square of your height in metres: BMI = kg ÷ m². If you use pounds and feet, the calculator converts them first (1 lb = 0.4536 kg, 1 inch = 2.54 cm), so both modes give the same answer. Example: 70 kg at 175 cm gives 70 ÷ (1.75 × 1.75) = 22.9.
BMI chart: WHO and Asian cut-offs
| Category | WHO (global) | Asian / Indian |
|---|---|---|
| Underweight | below 18.5 | below 18.5 |
| Normal | 18.5 – 24.9 | 18.5 – 22.9 |
| Overweight | 25 – 29.9 | 23 – 24.9 |
| Obese | 30 and above | 25 and above |
The WHO expert consultation (2004) noted that many Asian populations have higher health risk at a lower BMI, and Indian consensus guidelines use 23 and 25 as the overweight and obesity thresholds. Switch to “Asian / Indian” if those guidelines apply to you.
What your result means
The healthy weight range shows the weights that would put you in the normal band at your current height. BMI Prime is your BMI divided by the upper normal limit; a value above 1.0 means you are above the normal range.
Limits of BMI
BMI does not measure body fat directly. Muscular people can score high while being healthy, and older adults can score normal while carrying extra fat. It is not designed for children, teenagers or pregnant women, who need age- or stage-specific charts. Waist size is a useful second check: a waist over half your height is a common warning sign.
Privacy
The calculation runs entirely in your browser. Nothing you type is sent anywhere; your last inputs are only saved on this device so the page remembers them.
FAQ
What is a normal BMI?
For adults, the WHO normal range is 18.5 to 24.9. Under the Asian and Indian cut-offs, normal is 18.5 to 22.9.
Why is the Asian BMI range lower?
Studies summarised by the WHO found that many Asian populations develop diabetes and heart risk at lower BMI values, so lower thresholds are recommended for screening.
Is BMI the same for men and women?
Yes. The adult formula and cut-offs are the same for men and women, although body fat at a given BMI usually differs.
Can I use this BMI calculator for children?
No. Children and teenagers need BMI-for-age percentile charts. This tool is for adults aged 18 and over.
How do I calculate BMI in pounds and inches?
Use BMI = 703 × pounds ÷ inches². The imperial mode of this calculator does that for you.