BMI Calculator: WHO and Asian Cut-offs, Healthy Weight Range, kg or lb

How to use the calculator

Pick cm/kg or ft, in/lb, then enter height and weight. Your BMI and category update as you type.
WHO cut-offs are selected by default. Choose Korea / Asian (KSSO) to see the Korean adult cut-offs, which start lower.
Add your waist and sex if you want it compared with waist cut-offs. Both are optional.
For anyone under 20, choose Child or teen. Adult categories are not used for children.

BMI formula

BMI = weight (kg) ÷ height (m)²

In pounds and inches the same number is 703 × weight (lb) ÷ height (in)². For example, 170 cm and 70 kg gives 70 ÷ (1.7 × 1.7) = 24.2, and 5 ft 7 in (67 in) and 154 lb gives 703 × 154 ÷ 67² = 24.1. The calculator converts pounds and inches to kilograms and centimetres first, rounds BMI to one decimal place and then picks the category, because the category tables use one decimal place.

WHO adult BMI categories

WHO defines overweight in adults as a BMI of 25 or more and obesity as 30 or more. The full adult table is below. The same cut-offs apply to men and women.

Category	BMI (kg/m²)
Underweight	Below 18.5
Healthy weight	18.5–24.9
Pre-obesity (overweight)	25.0–29.9
Obesity class I	30.0–34.9
Obesity class II	35.0–39.9
Obesity class III	40.0 and above

Asian and Korean cut-offs

Health risks such as type 2 diabetes and high blood pressure rise at a lower BMI in many Asian populations. A WHO expert consultation published in The Lancet in 2004 kept the WHO categories for international comparison but added public health action points for Asian populations at BMI 23, 27.5, 32.5 and 37.5, and left the choice of national cut-offs to each country.

South Korea uses the Korean Society for the Study of Obesity (KSSO) guidelines. The 2024 (9th) edition keeps the same adult cut-offs as before:

KSSO category	BMI (kg/m²)
Underweight	Below 18.5
Normal	18.5–22.9
Pre-obesity (overweight)	23.0–24.9
Obesity class I	25.0–29.9
Obesity class II	30.0–34.9
Obesity class III (severe)	35.0 and above

That is why 170 cm and 70 kg (BMI 24.2) is a healthy weight under WHO cut-offs but pre-obesity under the Korean ones.

Waist size

BMI does not show where fat is stored, so waist size is often checked as well. The cut-offs usually attributed to WHO are above 94 cm (37 in) for men and above 80 cm (31.5 in) for women for increased risk, and above 102 cm (40.2 in) and 88 cm (34.6 in) for substantially increased risk. The 2008 WHO expert consultation notes that these figures come from European data. For Korean adults, KSSO uses 90 cm (35.4 in) or more for men and 85 cm (33.5 in) or more for women. The calculator uses the set that matches the cut-offs you choose.

Measure standing with feet about 25–30 cm apart, after breathing out, halfway between the lowest rib and the top of the hip bone, with the tape snug but not pressing in.

Healthy weight range for your height

The range shown is the healthy BMI band turned back into weight for your height: 18.5 × height (m)² up to 24.9 × height (m)² with WHO cut-offs, or up to 22.9 × height (m)² with Korean cut-offs. For 170 cm that is 53.5–72.0 kg (118–159 lb) with WHO and 53.5–66.2 kg with KSSO. The difference line only shows how far you are from that band. A personal target also depends on age, muscle and health, so treat it as a reference.

Worked examples

Height · weight	BMI	WHO	KSSO (Korea)
160 cm · 52 kg	20.3	Healthy weight	Normal
170 cm · 70 kg	24.2	Healthy weight	Pre-obesity
5 ft 9 in · 185 lb	27.3	Pre-obesity	Obesity class I

Children and teens

Adult categories are not used while children are still growing. WHO uses BMI-for-age: for ages 5–19, overweight is more than 1 standard deviation above the WHO Growth Reference median and obesity is more than 2. In Korea, KSSO recommends the 2017 Korean National Growth Charts from the Korea Disease Control and Prevention Agency for ages 2 and up, with the 85th percentile or above as overweight and the 95th or above as obesity. This calculator does not include those percentile tables, so use the WHO growth reference or the KDCA growth chart site instead.

What BMI cannot tell you

BMI cannot tell muscle from fat, so very muscular people can score high. KSSO also advises care when reading BMI for people with low muscle mass.
It is not used to judge weight during pregnancy.
It is a screening number. Whether anything needs attention depends on other checks such as blood pressure, blood sugar and cholesterol, which a doctor looks at together.

Sources

Frequently asked questions

How is BMI calculated?

Weight in kilograms divided by height in metres squared. In pounds and inches, multiply weight by 703 and divide by height in inches squared. 170 cm and 70 kg gives 24.2.

What is a healthy BMI for adults?

WHO uses 18.5 to 24.9 for adults. Korea uses 18.5 to 22.9 because health risks rise at lower BMI in Asian populations.

What are the Asian BMI cut-offs?

A 2004 WHO expert consultation added public health action points for Asian populations at 23, 27.5, 32.5 and 37.5. Korea's KSSO uses 23 for pre-obesity and 25, 30 and 35 for obesity classes I to III.

What waist size is too high?

Commonly cited WHO cut-offs are above 94 cm for men and above 80 cm for women for increased risk. In Korea the cut-offs are 90 cm for men and 85 cm for women.

Can children use this BMI calculator?

Adult categories do not apply to children and teens. Use BMI-for-age growth charts, such as the WHO growth reference for ages 5 to 19.

Is BMI a diagnosis?

No. BMI is a screening number that cannot tell muscle from fat. A doctor looks at it together with other checks.

BMI Calculator (WHO and Asian Cut-offs)

Enter height and weight