How to use the BMI calculator
- Choose Units: Metric or Imperial.
- For metric, enter Height in centimetres and Weight in kilograms.
- For imperial, enter Height (feet), Height (inches) and Weight in pounds.
- Read your BMI, your WHO category and your Asian-Indian category.
- Check the healthy weight range for your height under each set of thresholds, and the full category table below.
What it does and when to use it
BMI is a quick way to compare your weight with your height. Doctors and public health bodies use it as a first screening step, because it needs nothing more than a tape measure and a scale.
This calculator is different from many in one way: it shows two sets of categories side by side. The WHO thresholds are used internationally. The Asian-Indian thresholds come from a 2009 consensus statement and use lower cut-offs. The same BMI can therefore fall in different categories, as the first worked example shows.
Use it to check where you stand, to find a weight range to talk about with your doctor, or to track a trend over time. For calorie needs, see the TDEE Calculator. To plan meals around a calorie target, use the Macro Calculator. If you are also tracking blood pressure, the Blood Pressure Calculator explains readings.
How it works
- Metric: BMI = weight (kg) ÷ height (m)²
- Imperial: BMI = 703 × weight (lb) ÷ height (in)²
- Healthy weight range = lower and upper BMI limit × height (m)², shown in your units.
| WHO category | BMI | Asian-Indian category | BMI |
|---|---|---|---|
| Underweight | below 18.5 | Underweight | below 18.0 |
| Normal weight | 18.5–24.9 | Normal | 18.0–22.9 |
| Pre-obese (overweight) | 25.0–29.9 | Overweight | 23.0–24.9 |
| Obese class I | 30.0–34.9 | Obese | 25 and above |
| Obese class II | 35.0–39.9 | ||
| Obese class III | 40 and above |
The WHO thresholds come from the WHO Global Database on BMI. The Asian-Indian thresholds come from Misra and colleagues’ consensus statement (2009). The calculation runs in your browser.
Worked examples
170 cm and 68 kg. BMI = 68 ÷ 1.70² = 23.53 kg/m². That is Normal weight under WHO, but Overweight under the Asian-Indian thresholds. The healthy range for this height is 53.5–72 kg (WHO) or 52–66.2 kg (Asian-Indian).
5 ft 10 in and 200 lb. BMI = 703 × 200 ÷ 70² = 28.69. That is Pre-obese (overweight) under WHO and Obese under the Asian-Indian thresholds. The WHO healthy range for this height is 128.9–173.5 lb.
160 cm and 45 kg. BMI = 17.58 kg/m², which is Underweight under both sets. The healthy range starts at 47.4 kg (WHO) or 46.1 kg (Asian-Indian).
Limits and tips
- For adults only. It is not for children, teenagers or pregnancy.
- BMI does not measure body fat or show where fat is stored.
- Use the threshold set that matches your ancestry, and discuss the result with a doctor rather than acting on it alone.
- Measure height without shoes, and weigh yourself at a similar time of day if you track BMI over time.
Frequently asked questions
How is BMI calculated?
What are the WHO BMI categories?
Why does the calculator show an Asian-Indian category too?
Is BMI accurate for athletes?
Can I use it for children or during pregnancy?
What should I do with my result?
Sources
- WHO Global Database on Body Mass Index — international classification of adult underweight, overweight and obesity — World Health Organization, accessed 2026-10-02
- Body mass index among adults (indicators BMI < 18.5, ≥ 25, ≥ 30) — World Health Organization, accessed 2026-10-02
- Misra A et al. Consensus statement for diagnosis of obesity, abdominal obesity and the metabolic syndrome for Asian Indians. JAPI 2009;57:163-170 — Journal of the Association of Physicians of India (via PubMed), accessed 2026-10-02
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