BMI Calculator
Calculate your Body Mass Index. Free, no signup.
How It Works
Pick your unit system, enter your weight and height, and click Calculate. The tool computes your Body Mass Index and shows which category it falls into. Everything runs in your browser — your measurements are never uploaded.
BMI Categories
Underweight: below 18.5 • Normal: 18.5 – 24.9 • Overweight: 25 – 29.9 • Obese: 30 and above
BMI is a general indicator and does not account for muscle mass, bone density, or body composition. Consult a healthcare provider for personalized advice.
BMI Category Chart
| BMI range | Category |
|---|---|
| Below 18.5 | Underweight |
| 18.5 – 24.9 | Normal weight |
| 25.0 – 29.9 | Overweight |
| 30.0 and above | Obese |
These ranges apply to most adults aged 20 and over. Children, teenagers, and pregnant people are assessed differently, so the categories above may not apply.
Frequently Asked Questions
How is BMI calculated?
BMI is your weight divided by the square of your height. In metric units it is weight in kilograms divided by height in metres squared. In imperial units it is weight in pounds divided by height in inches squared, multiplied by 703. This tool does the math for you in either unit system.
How do I use the metric and imperial options?
Choose Metric to enter weight in kilograms and height in centimetres, or Imperial to enter weight in pounds and height in feet and inches. Enter your values and click Calculate to see your BMI and weight category.
What is a healthy BMI range?
The standard adult categories are: underweight below 18.5, normal weight from 18.5 to 24.9, overweight from 25 to 29.9, and obese at 30 and above. A BMI in the 18.5 to 24.9 range is generally considered healthy for adults.
Is BMI accurate for everyone?
BMI is a quick general indicator, not a full measure of health. It does not distinguish muscle from fat and does not account for bone density, body composition, age, or sex, so athletes and some body types can read high or low. Use it as a rough guide and consult a healthcare provider for personal advice.
Is my height and weight data kept private?
Yes. The calculation runs entirely in your browser with JavaScript and nothing is uploaded to a server. Your height and weight never leave your device.