BMI chart for adults, with the lower cut-offs for Asian backgrounds
Body mass index, or BMI, compares your weight with your height. Doctors use it as a quick first check. It is easy to work out, and you only need a scale and a tape measure.
How to work out your BMI
BMI = weight in kg ÷ (height in metres × height in metres)
For example, 80 kg at 1.75 m:
80 ÷ (1.75 × 1.75) = 80 ÷ 3.06 = 26.1
In pounds and inches, multiply by 703:
BMI = 703 × weight in lb ÷ (height in inches × height in inches)
The 703 is not a magic number. It turns pounds and inches into kilograms and metres.
The WHO chart
The World Health Organization’s classification for adults has not changed since its 2000 report:
| BMI | WHO class | Risk of other illness |
|---|---|---|
| Under 18.5 | Underweight | Low, but risk of other clinical problems increased |
| 18.5 to 24.9 | Normal range | Average |
| 25.0 to 29.9 | Pre-obese | Increased |
| 30.0 to 34.9 | Obese class I | Moderate |
| 35.0 to 39.9 | Obese class II | Severe |
| 40.0 and above | Obese class III | Very severe |
One detail surprises people. In the WHO report, “overweight” means every BMI of 25 and above, obesity included. The band from 25 to 29.9 is called pre-obese. Most websites and apps call that band overweight, and that is what most readers expect.
The cut-offs for Asian backgrounds
Many people of Asian background develop diabetes and heart disease at a lower BMI than the chart above suggests. In 2004, a WHO expert consultation looked at the evidence. It reported that the BMI at which risk rises varies from 22 to 25 between different Asian populations.
The consultation kept the international chart. It added four points for public health action at 23, 27.5, 32.5 and 37.5. For many Asian populations it suggested these groups:
| BMI | Suggested category |
|---|---|
| Under 18.5 | Underweight |
| 18.5 to 23 | Increasing but acceptable risk |
| 23 to 27.5 | Increased risk |
| 27.5 and above | High risk |
England’s National Institute for Health and Care Excellence (NICE) goes further and wider. Its obesity guideline tells doctors to use lower thresholds for people with a South Asian, Chinese, other Asian, Middle Eastern, Black African or African-Caribbean background:
- Overweight: BMI 23 to 27.4
- Obesity: BMI 27.5 or above
So if you are from Bangladesh, India, Pakistan, China or anywhere else on that list, a BMI of 24 is not in the clear. It is in the band where risk has started to rise.
What this means at one height
At 1.70 m tall:
| BMI | Weight at 1.70 m |
|---|---|
| 18.5 | 53.5 kg |
| 23.0 | 66.5 kg |
| 25.0 | 72.3 kg |
| 27.5 | 79.5 kg |
| 30.0 | 86.7 kg |
The gap between the two scales is about 6 kg at this height. That is the difference between “normal” on one chart and “increased risk” on the other. In Downtrend you pick the scale that fits you, and it shows each band’s weight range at your height and how far you are from the next one.
What BMI cannot tell you
BMI does not know what your weight is made of. A muscular person can have a high BMI and little fat. Someone with a normal BMI can carry a lot of fat around the middle, which is the fat NICE asks doctors to check with a waist measurement. NICE tells doctors to read BMI with caution for both reasons.
In 2025 a commission of experts writing in The Lancet Diabetes and Endocrinology went further. It argued that obesity should not be diagnosed on BMI alone, and that a second measure, such as waist size, should confirm it.
The easiest second measure to take at home is your waist-to-height ratio. If you want a number for fat itself, a tape measure method can estimate it.
Sources
- World Health Organization. Obesity: preventing and managing the global epidemic. WHO Technical Report Series 894, 2000. Table 2.1.
- WHO Expert Consultation. Appropriate body-mass index for Asian populations and its implications for policy and intervention strategies. The Lancet, 2004.
- NICE. Overweight and obesity management, guideline NG246, 2025. Recommendations 1.9.7, 1.9.11 and 1.9.12.
- Rubino F and others. Definition and diagnostic criteria of clinical obesity. The Lancet Diabetes and Endocrinology, 2025.
This article is general information, not medical advice. Talk to a doctor before a big change to what you eat or how you train, and especially if you are pregnant, under 18 or have a health condition.