BMI Calculator
Work out your body mass index in seconds — in feet and inches or centimetres, kilograms or pounds. See your category on the WHO or Asian scale, the healthy weight for your height and how far you are from it.
At a glance
- BMI = weight in kg ÷ (height in m)². In pounds and inches the same formula is 703 × lb ÷ in².
- WHO adult categories: below 18.5 underweight, 18.5–24.9 healthy, 25–29.9 overweight and 30 or more obesity (classes I, II and III from 30, 35 and 40).
- Asian cut-offs (WHO Asia-Pacific classification, also used by Indian guidelines): 18.5–22.9 healthy, 23–24.9 overweight and 25 or more obesity.
- Shows the healthy weight range for your height and how much you would need to lose or gain to reach it.
- Optional waist-to-height ratio, graded with the NICE (2022) boundaries: 0.4–0.49 healthy, 0.5–0.59 increased health risk, 0.6 or more high risk.
- Adult categories apply from age 18. Under 18, BMI has to be read on age- and sex-specific growth charts.
- Height in feet and inches or cm, weight in kg or pounds, in any combination. Nothing you enter leaves your browser.
Step by step
How to calculate your BMI
- 1
Enter your height
Type your height in feet and inches, or switch to centimetres.
- 2
Enter your weight
Type your weight in kilograms, or switch to pounds. Weigh yourself in the morning, in light clothes, for the most consistent number.
- 3
Choose the categories
Keep WHO (international), or pick Asian / Indian if you are of South Asian, Chinese or other Asian descent. Add your age and waist size for more context.
- 4
Read your result
See your BMI and category on the scale, your healthy weight range and how far you are from it.
Features
Everything you need, nothing you don’t
Feet and kilos together
Enter height in feet and inches and weight in kilograms — the way most people in India know them — or any other mix of units.
Asian and Indian cut-offs
One tap switches to the lower thresholds recommended for people of Asian descent, who face higher health risks at a lower BMI.
Your healthy weight range
See the exact weight range that gives a healthy BMI at your height, and the weight for every other category too.
Waist-to-height ratio
Add your waist size to check belly fat — a better guide to heart and diabetes risk than BMI alone.
Shows the working
The formula is written out with your numbers, so you can check the result by hand.
Private
Your height, weight and age are never uploaded, stored or shared.
BMI chart for adults
| Category | WHO (international) | Asian / Indian |
|---|---|---|
| Underweight | Below 18.5 | Below 18.5 |
| Healthy weight | 18.5 – 24.9 | 18.5 – 22.9 |
| Overweight | 25.0 – 29.9 | 23.0 – 24.9 |
| Obesity | 30.0 or more | 25.0 or more |
How BMI is calculated
Divide your weight in kilograms by your height in metres squared. For someone who weighs 68 kg and is 1.70 m tall: 68 ÷ (1.70 × 1.70) = 68 ÷ 2.89 = 23.5.
In pounds and inches, multiply by 703: for 150 lb and 5 ft 5 in (65 in), 703 × 150 ÷ 65² = 105,450 ÷ 4,225 = 25.0. The calculator uses exact unit conversions, so both methods agree.
Why Asians have lower BMI cut-offs
At the same BMI, people of South Asian descent tend to carry more body fat, especially around the waist, and develop type 2 diabetes and heart disease at a lower BMI than people of European descent.
That is why the WHO Asia-Pacific classification and Indian consensus guidelines treat a BMI of 23 as overweight and 25 as obesity. If you are of Asian descent, a BMI of 24 is a reason to act, even though it is “healthy” on the international scale.
What BMI doesn’t tell you
- Muscle vs fat: muscular people and athletes can have a high BMI without excess fat.
- Where fat sits: fat around the waist carries more risk. Your waist should be less than half your height.
- Older adults: muscle is lost with age, so body fat can be higher than BMI suggests.
- Pregnancy: BMI isn’t valid during pregnancy; use your pre-pregnancy weight when a doctor asks for it.
- Children and teens: BMI is compared with others of the same age and sex on growth charts rather than with the adult categories.
FAQ
Frequently asked questions
What is a healthy BMI?
Which cut-offs should I use if I’m Indian?
How is BMI calculated?
Is BMI accurate?
Is BMI different for men and women?
Can I use this calculator for children?
What is BMI Prime?
What is a healthy waist-to-height ratio?
Is my data saved?
Keep going
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