BMI Explained: What Your Number Means (and Indian Ranges)
Body Mass Index (BMI) is the most common quick screen for whether your weight is in a healthy range for your height. It is easy to calculate and useful as a starting point, but it is worth understanding both what it tells you and what it doesn’t.
How BMI is calculated
BMI is your weight in kilograms divided by the square of your height in metres (kg/m²). So a person who is 1.7 m tall and weighs 70 kg has a BMI of 70 ÷ (1.7 × 1.7) = 24.2. You don’t need to do this by hand — but knowing the formula makes the number less mysterious.
BMI categories
Your BMI falls into one of four categories. The standard WHO thresholds are used worldwide; the Asian/Indian thresholds are lower because South Asian populations face higher health risks at a given BMI.
BMI categories under WHO and Asian/Indian standards (kg/m²).
| Category | WHO standard | Asian / Indian |
|---|---|---|
| Underweight | Below 18.5 | Below 18.5 |
| Normal weight | 18.5 – 24.9 | 18.5 – 22.9 |
| Overweight | 25.0 – 29.9 | 23.0 – 24.9 |
| Obese | 30.0 and above | 25.0 and above |
Why Indian ranges are different
Research shows that people of South Asian origin tend to carry more body fat and face higher health risks at a lower BMI than the standard cut-offs suggest. For this reason, many Indian guidelines treat a BMI of 23 and above as overweight and 25 and above as obese. Our calculator can show these Asian/Indian ranges alongside the standard ones.
The limits of BMI
BMI only uses height and weight, so it can’t tell muscle from fat or show where fat is stored. A muscular athlete may have a “high” BMI while being very healthy, and two people with the same BMI can have very different body compositions. Treat BMI as a first indicator, not a diagnosis, and consider waist measurement and a doctor’s advice for the full picture.
To find your number and see both the standard and Indian categories, use our BMI Calculator with metric or imperial units.
Frequently asked questions
How do I calculate BMI from height and weight?
Divide your weight in kilograms by your height in metres squared (kg/m²). For example, 70 kg at 1.7 m is 70 ÷ (1.7 × 1.7) = 24.2. The calculator does it for metric or imperial inputs.
What is a healthy BMI?
For most adults, 18.5 to 24.9 is considered healthy under WHO guidelines. For people of South Asian descent, the healthy range is often set a little lower, at 18.5 to 22.9.
Why are the Asian/Indian BMI ranges lower?
Research shows people of South Asian origin tend to develop health risks such as diabetes and heart disease at a lower BMI, so Indian guidelines use lower overweight (23) and obese (25) cut-offs.
Is BMI accurate for athletes?
Not always. BMI uses only height and weight, so it cannot tell muscle from fat — a muscular person can have a high BMI while being healthy. Treat it as a screening tool, not a diagnosis.
Try it yourself
Open the BMI Calculator →About the author
The Tiny Web Tools Team
The Tiny Web Tools team builds and maintains the free calculators and converters on this site. We write these guides to explain the formulas behind our tools in plain English, and we review them when rules, rates, or official specifications change.
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