BMI Calculator
Calculate your body mass index in US units (feet, inches, pounds) or metric units, see your WHO weight category and the healthy weight range for your height. Asian cut-offs are shown for reference.
Enter your height and weight, then tap Calculate BMI.
BMI categories for adults
WHO classification (used in the US, UK and most countries)
| Category | BMI (kg/m²) |
|---|---|
| Underweight | Below 18.5 |
| Normal (healthy) weight | 18.5 – 24.9 |
| Overweight (pre-obesity) | 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 cut-offs (Korean Society for the Study of Obesity, 2022)
| Category | BMI (kg/m²) |
|---|---|
| Underweight | Below 18.5 |
| Normal | 18.5 – 22.9 |
| Pre-obesity (at risk) | 23.0 – 24.9 |
| Obesity class I | 25.0 – 29.9 |
| Obesity class II | 30.0 – 34.9 |
| Obesity class III | 35.0 and above |
Abdominal obesity (Asian cut-off): waist 90 cm (35.4 in) or more in men, 85 cm (33.5 in) or more in women.
Your result is placed on the WHO scale first. The Asian row is highlighted too, because people of East and South Asian descent tend to develop type 2 diabetes and heart disease at a lower BMI.
How BMI is calculated
Body mass index is your weight divided by the square of your height. In metric units it is kg ÷ m². With pounds and inches, multiply by 703: BMI = 703 × weight (lb) ÷ height (in)².
Example
A person who is 5 ft 9 in (69 in) and weighs 160 lb has a BMI of 703 × 160 ÷ 69² ≈ 23.6, which is in the WHO normal range. The same person is 175.3 cm and 72.6 kg: 72.6 ÷ 1.753² ≈ 23.6. Under the Asian cut-offs the same BMI falls in the “pre-obesity” band (23.0–24.9).
Healthy weight range for your height
The calculator also turns the normal BMI band back into pounds or kilograms for your height (18.5 × height² to 24.9 × height²). For a 5 ft 9 in adult that is about 125–169 lb (57–76 kg). For a target based on frame size and common clinical formulas, try the Ideal Weight Calculator, and to plan how much to eat, use the BMR & Calorie Calculator.
Waist size and abdominal fat
BMI says nothing about where fat is stored. Fat around the belly is linked to a higher risk of type 2 diabetes and heart disease, so the waist check compares your measurement with two thresholds:
- WHO / NIH: substantially increased risk above 102 cm (40 in) for men and 88 cm (35 in) for women.
- Asian cut-off (KSSO): abdominal obesity at 90 cm (35.4 in) or more for men and 85 cm (33.5 in) or more for women.
The WHO expert consultation also describes a lower “increased risk” level of 94 cm (37 in) for men and 80 cm (31.5 in) for women, and notes that the best cut-off differs between ethnic groups.
Frequently asked questions
Is BMI accurate for athletes?
Not always. BMI cannot tell muscle from fat, so muscular people can be classed as overweight while having little body fat. Older adults who have lost muscle may have more body fat than their BMI suggests.
Can I use this for children or during pregnancy?
No. Children and teens aged 2–19 are assessed with BMI-for-age percentiles, and BMI does not apply during pregnancy. These categories are for adults aged 20 and over.
Why show Asian cut-offs?
A WHO expert consultation (2004) found that many Asian populations have a higher risk of diabetes and cardiovascular disease at BMIs below 25 and suggested extra public-health action points at 23 and 27.5. Several Asian countries, including Korea, use lower cut-offs in practice. If you have Asian heritage, it is worth knowing where you fall on both scales.
Is my data saved?
Your inputs are sent to our calculation server only to compute the result and are not stored there. Your browser may remember the last values you entered on this device; use the “Clear” link that appears above the form to remove them.
Sources
- World Health Organization, Obesity and overweight fact sheet.
- WHO Expert Consultation, Appropriate body-mass index for Asian populations, Lancet 2004;363:157–63.
- WHO, Waist circumference and waist–hip ratio: report of a WHO expert consultation (2008).
- NHLBI/NIH, Clinical Guidelines on the Identification, Evaluation, and Treatment of Overweight and Obesity in Adults (1998).
- Korean Society for the Study of Obesity, 2022 Clinical Practice Guidelines for Obesity (Asian BMI and waist cut-offs).
This calculator is for general information and does not replace advice from a doctor.