Get your body mass index and its WHO band as you type, in metric or imperial. It’s worked out on your device.
Units
cm
kg
ft
in
lb
cm
kg
ft
in
lb
Result
Your result will appear here.
22.5 kg/m²
BMI
WHO band
Normal weight (18.5–24.9)
Weight at BMI 18.5–24.9
53.5–72.0 kg
How it’s calculated
BMI = 65 kg ÷ (1.70 m)² = 22.5
Imperial units are converted exactly: 1 lb = 0.45359237 kg, 1 in = 0.0254 m.
The bands are the WHO adult categories, shown as labels only.
BMI doesn’t apply to children or during pregnancy.
22.4 kg/m²
BMI
WHO band
Normal weight (18.5–24.9)
Weight at BMI 18.5–24.9
118.1–159.0 lb
How it’s calculated
143 lb = 64.86 kg, 5 ft 7 in = 1.70 m; BMI = 64.86 kg ÷ (1.70 m)² = 22.4
Imperial units are converted exactly: 1 lb = 0.45359237 kg, 1 in = 0.0254 m.
The bands are the WHO adult categories, shown as labels only.
BMI doesn’t apply to children or during pregnancy.
What it does
The BMI calculator divides your weight by the square of your height and shows:
BMI in kg/m², to one decimal, such as 22.5 kg/m².
WHO band: the adult category that BMI falls in, such as Normal weight (18.5–24.9).
Weight at BMI 18.5–24.9: the weights that give a BMI from 18.5 to 24.9 at your height, in kg or lb.
The answer updates as you type.
How to use it
Under Units, choose Metric (cm and kg) or Imperial (feet, inches and pounds).
Enter your height and weight.
Select Copy result to put the answer on your clipboard.
The calculator remembers your choice of units on this device. Your height and weight aren’t kept: after a reload the form shows its example values again.
How it’s calculated
BMI = weight in kg ÷ (height in m)². At 170 cm and 65 kg: 65 kg ÷ (1.70 m)² = 22.5.
In imperial, the height is 12 × feet + inches, times 0.0254 m, and the weight is pounds times 0.45359237 kg. These are the exact definitions of the units. So 5 ft 7 in and 143 lb are 1.70 m and 64.86 kg, and the BMI is 22.4.
The BMI is rounded once, to one decimal, and the band is read from that rounded value. A BMI of 24.95 shows as 25.0, so it’s in Pre-obesity (25.0–29.9).
Good to know
Height goes from 50 to 272 cm, or 1 to 8 ft and 0 to 11.9 in. Weight goes from 2 to 650 kg, or 4 to 1,433 lb.
The bands are the WHO adult categories, shown as labels only. They don’t apply to children or during pregnancy.
BMI doesn’t measure body fat or muscle, and it isn’t a diagnosis.
Privacy
Everything is worked out in your browser, on your device. Nothing you type is uploaded. Only your choice of units is kept, in this browser’s storage, so the page can show it again.
Frequently asked questions
How is BMI worked out?
BMI is your weight in kilograms divided by the square of your height in metres: kg ÷ m². At 170 cm and 65 kg that is 65 ÷ (1.70 × 1.70) = 22.5 kg/m².
What are the WHO bands?
The World Health Organization groups adult BMI into six bands: Underweight below 18.5, Normal weight from 18.5 to 24.9, Pre-obesity from 25.0 to 29.9, Obesity class I from 30.0 to 34.9, Obesity class II from 35.0 to 39.9 and Obesity class III from 40.0. The band is read from the BMI as shown, rounded to one decimal.
Can I use feet, inches and pounds?
Yes. Choose Imperial under Units. Your height and weight are converted exactly, with 1 inch = 0.0254 m and 1 pound = 0.45359237 kg, so the same body gives the same BMI in either unit.
Does it work for children?
No. Children and teenagers are compared with others of the same age and sex on growth charts, not with the adult bands. BMI also doesn’t apply during pregnancy.
What doesn’t BMI tell you?
BMI uses only height and weight. It can’t tell muscle from fat, or show where fat sits on the body, and the same number can mean different things for different people. It’s a screening measure used in statistics; this page shows the number and its WHO label, and nothing more.