BMI Calculator
Calculate your Body Mass Index from height and weight. Compare adult BMI categories with an easy-to-read result and a BMI-based reference weight range.
Calculate Your BMI
Enter your measurements and choose your preferred unit system.
Your BMI Result
✓ CalculatedBMI is a screening measure, not a diagnosis or a direct body-fat measurement. It does not account for individual body composition or pregnancy. Ask a health professional for personalized guidance.
How to use this BMI Calculator
Get a quick BMI estimate in just three steps. No account or registration is needed.
Choose Metric (cm/kg) or Imperial (feet, inches and pounds).
Add your height, weight and age. Check the values before calculating.
See the BMI number, adult category and BMI-based weight reference range.
How is Body Mass Index calculated?
Metric formula: BMI = weight (kg) ÷ [height (m) × height (m)]. Imperial formula: BMI = weight (lb) × 703 ÷ [height (in)]² (approximation; the tool converts to metric internally for consistent results).
Example: A person weighing 70 kg and measuring 170 cm has BMI = 70 ÷ (1.70 × 1.70) = 24.2 when rounded to one decimal place.
For adults 20 or older, the following standard BMI classifications are used. Categories are determined from the unrounded number, so values near category boundaries are interpreted correctly.
| Adult BMI category | BMI range (kg/m²) |
|---|---|
| Underweight | Below 18.5 |
| Healthy Weight | 18.5 to less than 25 |
| Overweight | 25 to less than 30 |
| Obesity | 30 or higher |
Source: CDC — Adult BMI Categories. BMI should be considered alongside other health information.
What does your BMI result mean?
BMI is useful for initial screening, but it cannot diagnose a health condition. For example, people with more muscle may have a relatively high BMI without having high body fat. The healthy-weight reference range shown above is calculated only from adult BMI thresholds and height; it is not a personal goal or medical recommendation.
For children and teens aged 2–19: The same BMI formula can be calculated, but adult weight classifications are not appropriate. BMI-for-age percentiles require age and sex and a dedicated child/teen calculator. This page therefore hides adult category and reference-weight results when the entered age is under 20. See the CDC child and teen BMI information.
During pregnancy, BMI also requires different interpretation. Consult your healthcare team if you need health guidance.
Frequently Asked Questions
What is a BMI Calculator?
It estimates Body Mass Index from height and weight, then gives the corresponding standard weight-status category for adults aged 20 and older.
How do I calculate BMI using kg and cm?
Divide weight in kilograms by height in meters squared. For example, 70 kg and 170 cm give a BMI of approximately 24.2.
What is considered a healthy BMI for adults?
For adults 20 and older, a BMI from 18.5 up to but not including 25 is classified as healthy weight by the CDC. BMI is only one health screening measure.
Can I use feet, inches, and pounds?
Yes. Switch to Imperial, enter feet and inches plus pounds, and the calculator automatically converts measurements before calculating BMI.
Is BMI different for men and women?
The standard adult BMI calculation and cutoff categories are the same for adults regardless of sex, but body composition and individual risk can vary.
Is this BMI Calculator suitable for a teenager?
It can calculate the number, but will not display an adult category for anyone younger than 20. Children and teens need BMI-for-age interpretation using a separate calculator.
Does BMI measure body fat directly?
No. BMI relates weight to height. It does not directly measure fat or distinguish muscle from fat.
Are my weight and height stored?
This calculator computes results locally in your browser. Its own code does not send input values to a server. Your site's other scripts, hosting, or analytics may have separate privacy practices.