BMI Calculator
Calculate your Body Mass Index (BMI) instantly. Enter height and weight to get BMI with interpretation. Supports metric and imperial units.
About this calculator
Body mass index (BMI) compares your weight with your height and puts the result into a category from underweight to obese. This BMI calculator accepts metric or imperial units and also shows the weight range that corresponds to a healthy BMI for your height.
BMI is a quick screening number, not a diagnosis. It cannot tell muscle from fat, and it ignores age, sex and where the body stores weight, so use it as a starting point for a conversation with a doctor.
How to use it
- Choose metric (cm and kg) or imperial (feet, inches and pounds).
- Enter your height and weight.
- Press calculate to see your BMI, the category and the healthy weight range for your height.
The BMI formula
BMI = weight (kg) / height (m)2
This tool uses Asia-Pacific style cut-offs that are common in India: below 18.5 underweight, 18.5 to 22.9 normal, 23 to 24.9 overweight (at risk), 25 to 29.9 overweight, and 30 or above obese. The WHO international cut-off for overweight starts at 25.
Worked example
70 kg and 170 cm
| Step | Value |
|---|---|
| Height in metres | 1.70 m |
| BMI = 70 / (1.70 × 1.70) | 24.2 |
| Category | Overweight (Asian threshold) |
| Weight for BMI 18.5 to 22.9 | 53.5 kg to 66.2 kg |
Tips and common mistakes
- Athletes and people with high muscle mass can show a high BMI without excess fat.
- Waist circumference is a useful second measure, since fat around the waist carries higher health risk.
- BMI categories for children and teenagers use age and sex charts, so this tool is for adults.
- Weigh yourself at the same time of day for comparable readings.
Frequently asked questions
What is a healthy BMI?
For adults, 18.5 to 24.9 is the usual WHO healthy range. Many Indian guidelines use 18.5 to 22.9 as normal because health risks rise at lower BMI in South Asian populations.
Is BMI accurate?
It is a reasonable population screen but a poor individual measure. It does not separate fat from muscle or show fat distribution.
Can I use this BMI calculator for children?
No. Children's BMI is judged against age and sex percentiles, so ask a paediatrician or use a growth chart.
Why does this tool use different cut-offs?
Studies show South Asians develop diabetes and heart disease at lower BMI than Europeans, so Asian guidelines set lower overweight thresholds.
How can I lower my BMI safely?
Gradual changes in diet, activity and sleep work better than crash diets. A doctor or dietitian can set a plan that suits your health.
Does BMI apply during pregnancy?
No. BMI is not meant to be used during pregnancy. Speak to your doctor for weight-gain guidance.