BMI Calculator
Calculate your Body Mass Index using your weight and height. BMI is a quick screening measure that can help estimate whether your weight is in a general healthy range for your height.
BMI is a screening measure for adults and is not a medical diagnosis.
How this calculator works
How to use this calculator
1. Enter your weight.
2. Choose kilograms or pounds.
3. Enter your height.
4. Choose centimeters, feet, or inches.
5. Click Calculate BMI to see your BMI number and category.
Formula used
BMI = weight in kilograms ÷ height in meters²
If weight is entered in pounds, it is converted to kilograms:
weight kg = weight lb × 0.453592
If height is entered in centimeters, it is converted to meters:
height m = height cm ÷ 100
Example calculation
Example: 70 kg and 170 cm
Height in meters = 170 ÷ 100 = 1.70 m
BMI = 70 ÷ (1.70 × 1.70)
BMI = 70 ÷ 2.89
BMI = 24.2
What the result means
For adults, BMI is usually grouped into these ranges:
Underweight: below 18.5
Healthy weight: 18.5 to less than 25
Overweight: 25 to less than 30
Obesity: 30 or greater
BMI is a screening measure, not a medical diagnosis. It does not directly measure body fat or account for muscle mass, age, sex, or body composition.
Frequently asked questions
Is BMI accurate for everyone?
BMI is useful as a general screening tool, but it does not directly measure body fat. Athletes, older adults, and people with higher muscle mass may need additional measurements.
Can children use this BMI calculator?
This calculator is designed for adults. Children and teens need age- and sex-specific BMI percentile charts.
What is a healthy BMI?
For most adults, a BMI from 18.5 to less than 25 is considered the healthy weight range.
Why do I need to enter both height and weight?
BMI compares your weight relative to your height, so both values are required.