# BMI Calculator: WHO, Sri Lanka and Asia-Pacific Cut-offs, Metric and Imperial

Page: https://hirantha.me/tools/bmi-calculator
Part of: Hirantha Sandaruwan Lakshan free tools (https://hirantha.me/tools)
Updated: 2026-10-13

Work out your BMI in kg and cm or lb and feet, see where it falls on the WHO, Sri Lanka and Asia-Pacific cut-offs, and get a weight range for your height.

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Enter your weight, height and age and the calculator gives your body mass index (BMI) to one decimal, where it falls on four sets of published cut-offs, and the weight range for your height on each. You can pick the WHO international cut-offs (18.5, 25, 30, 35 and 40), the Sri Lanka Ministry of Health table, the WHO Western Pacific Asia-Pacific table or the WHO 2004 Asian action points. It is for adults aged 20 and over. This is general information, not medical advice, and BMI is a screening measure, not a diagnosis. Nothing you type leaves your device.

BMI is weight in kilograms divided by height in metres squared. For 70 kg at 170 cm it is 70 divided by 1.7 x 1.7, which is 70 / 2.89 = 24.2. In pounds, feet and inches the tool converts with the exact factors (1 lb = 0.45359237 kg, 1 inch = 2.54 cm) before it divides. The result is rounded half up to one decimal and then matched to a range, so the number you see is the number that was matched.

The WHO international classification, as reproduced in the WHO Western Pacific report of 2000 (which cites WHO 1998), is: underweight below 18.5, normal range 18.5 to 24.9, pre-obese 25.0 to 29.9, obese class I 30.0 to 34.9, class II 35.0 to 39.9 and class III 40.0 and above. The WHO obesity and overweight fact sheet uses the same two main lines for adults: overweight from 25 and obesity from 30.

The Asian cut-offs are lower because studies of Asian populations found that the health risks linked to weight, such as type 2 diabetes and heart disease, are already substantial below a BMI of 25. A WHO expert consultation in 2004 found that the BMI where risk starts to show varies from 22 to 25 across Asian populations, and where it is high from 26 to 31. It did not set a new classification for each population. It kept the WHO cut-offs as the international classification and named further public health action points at 23.0, 27.5, 32.5 and 37.5, and left countries to decide how to define increased risk. The WHO Western Pacific report of 2000 had earlier proposed, as provisional cut-offs for Asian adults, a normal range of 18.5 to 22.9, an at-risk band of 23.0 to 24.9, obese I at 25.0 to 29.9 and obese II at 30.0 and above.

The Sri Lanka Ministry of Health Nutrition Division's Check your BMI table, which it describes as Asian cut-off values used in Sri Lanka for adults aged 20 and over, lists underweight below 18.5, normal 18.5 to 22.9, risk to overweight 23.0 to 24.9, overweight 25.0 to 29.9 and obese 30.0 and above. The Ministry's 2018 Guideline on Management of Overweight and Obesity among Adults in Sri Lanka prints normal as 18.5 to 24.9 in its table, adds obesity classes at 30, 35 and 40, and says a BMI of 23 to 24.9 is an increased risk for overweight and a trigger point for lifestyle changes. The Ministry scale in this tool combines the two: it splits at 23 and uses the classes at 35 and 40 from the guideline.

The weight range for your height is the weight that gives a BMI of 18.5 up to the top of the chosen scale's normal range (24.9 on the WHO scale, 22.9 on the Asian scales), worked out as BMI times height squared. BMI does not tell muscle from fat, does not show where fat is carried, and has no age term. The Sri Lanka guideline also uses waist circumference, describing 90 cm or more for men and 80 cm or more for women as abdominal adiposity. For children and teenagers the WHO uses BMI-for-age growth references (ages 5 to 19) and the CDC uses BMI percentiles (ages 2 to 19), which is why this tool is for adults aged 20 and over.

Adult BMI cut-offs on the four scales used by this calculator:
| BMI | WHO adult | Sri Lanka Ministry of Health | Asia-Pacific (WHO Western Pacific, 2000) | WHO 2004 action points |
| --- | --- | --- | --- | --- |
| Below 18.5 | Underweight | Underweight | Underweight | Below 18.5 |
| 18.5 to 22.9 | Normal range | Normal | Normal range | Below the 23.0 point |
| 23.0 to 24.9 | Normal range | Risk to overweight | Overweight, at risk | Past the 23.0 point |
| 25.0 to 27.4 | Pre-obese (overweight) | Overweight | Obese I | Past the 23.0 point |
| 27.5 to 29.9 | Pre-obese (overweight) | Overweight | Obese I | Past the 27.5 point |
| 30.0 to 32.4 | Obesity class I | Obesity class 1 | Obese II | Past the 27.5 point |
| 32.5 to 34.9 | Obesity class I | Obesity class 1 | Obese II | Past the 32.5 point |
| 35.0 to 37.4 | Obesity class II | Obesity class 2 | Obese II | Past the 32.5 point |
| 37.5 to 39.9 | Obesity class II | Obesity class 2 | Obese II | Past the 37.5 point |
| 40.0 and above | Obesity class III | Obesity class 3 | Obese II | Past the 37.5 point |

Q: What is a healthy BMI?
A: On the WHO international scale the normal range is 18.5 to 24.9. On the Asian cut-offs in the Sri Lanka Ministry of Health Nutrition Division table and in the WHO Western Pacific Asia-Pacific table the normal range is 18.5 to 22.9. A BMI in a normal range does not on its own mean a person is healthy, and one outside it does not mean they are unwell. These are screening ranges. Ask a doctor about your own health.

Q: Which BMI scale should a Sri Lankan use?
A: The Ministry of Health Nutrition Division publishes a table of Asian cut-off values for use in Sri Lanka for adults aged 20 and over (normal 18.5 to 22.9, risk to overweight 23.0 to 24.9, overweight 25.0 to 29.9, obese 30.0 and above). The Ministry's 2018 adult obesity guideline treats 23 to 24.9 as an increased risk for overweight. Your doctor will say which one applies to you. This tool lets you switch and shows all four side by side.

Q: Why are the Asian BMI cut-offs lower than the WHO ones?
A: Because studies found that the proportion of Asian people at high risk of type 2 diabetes and heart disease is substantial at BMIs below 25. The WHO expert consultation of 2004 reviewed this, found the risk threshold differs between Asian populations (22 to 25 for observed risk, 26 to 31 for high risk), kept the WHO cut-offs as the international ones, and added public health action points at 23.0, 27.5, 32.5 and 37.5.

Q: Is BMI accurate for athletes or very muscular people?
A: Not on its own. The Sri Lanka guideline says BMI may overestimate the degree of obesity in people who are muscular, just as it may underestimate it in people with low lean mass and relatively high fat mass. The CDC adds that BMI does not distinguish between fat, muscle and bone mass, or show where fat is carried.

Q: Can I use this BMI calculator for a child or teenager?
A: No. Children and teenagers are still growing, so the adult cut-offs do not apply. The WHO uses BMI-for-age growth references for ages 5 to 19, and the CDC uses BMI percentiles for ages 2 to 19. Ask a doctor or school health nurse. This tool asks for age and stops below 20 for that reason.

Q: Does BMI diagnose obesity?
A: No. The CDC describes BMI as a screening measure, and the Sri Lanka guideline says the complete diagnosis of obesity does not simply depend on the BMI level but also on the impact of weight gain on health. A doctor can look at your waist measurement, blood pressure, blood tests and history.

Q: How do I calculate BMI in pounds and inches?
A: Switch the units to imperial and type your weight in pounds and your height in feet and inches. The tool converts to kilograms and metres with exact factors (1 lb = 0.45359237 kg, 1 inch = 2.54 cm) and divides. If you change units part way through, the numbers you typed are converted, not cleared.

Q: What should I do if my BMI is outside the normal range?
A: A single number does not tell you what to do. Talk to a doctor or another qualified health professional. The CDC says BMI should be considered with other factors, such as blood pressure, cholesterol levels and a physical examination. If you are pregnant, ask your midwife or doctor, because these adult ranges may not apply during pregnancy.

Sources: WHO Western Pacific Region, The Asia-Pacific perspective: redefining obesity and its treatment, 2000 (the WHO classification and the proposed Asian classification), checked 2026-10-13 (https://iris.who.int/items/a74d8440-5c1d-4237-9559-3f729058587b); WHO Expert Consultation, Appropriate body-mass index for Asian populations and its implications for policy and intervention strategies, The Lancet 2004 (abstract), checked 2026-10-13 (https://pubmed.ncbi.nlm.nih.gov/14726171/); Ministry of Health Sri Lanka, Nutrition Division, Check your BMI (Asian cut-off values used in Sri Lanka for adults aged 20 and over), checked 2026-10-13 (https://nutrition.health.gov.lk/english/); Ministry of Health Sri Lanka, Non Communicable Disease Unit, Guideline on Management of Overweight and Obesity among Adults in Sri Lanka, first edition 2018, checked 2026-10-13 (https://www.ncd.health.gov.lk/images/pdf/Guildlines/Guideline_Obesity.pdf); WHO, Obesity and overweight fact sheet (adult cut-offs 25 and 30; BMI-for-age for ages 5 to 19), checked 2026-10-13 (https://www.who.int/news-room/fact-sheets/detail/obesity-and-overweight); CDC, About BMI (screening measure, what BMI does not show, adults aged 20 and over, children and teens 2 to 19 use a different tool), checked 2026-10-13 (https://www.cdc.gov/bmi/about/index.html); CDC, Adult BMI Calculator (category table for adults 20 and older), checked 2026-10-13 (https://www.cdc.gov/bmi/adult-calculator/index.html); WHO, Growth reference data for 5 to 19 years (the BMI-for-age reference used for children and adolescents), checked 2026-10-13 (https://www.who.int/tools/growth-reference-data-for-5to19-years)

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