How to use the BMI Calculator
- Choose US or metric units.
- Enter your height and weight.
- See your BMI, category and healthy weight range.
About this tool
Body Mass Index (BMI) is a quick screening number calculated from height and weight: BMI = weight (kg) ÷ height (m)². Health organisations such as the CDC and WHO use these adult categories:
- Below 18.5 — Underweight
- 18.5 – 24.9 — Healthy weight
- 25 – 29.9 — Overweight
- 30 and above — Obesity
BMI doesn’t measure body fat directly. Very muscular people can have a high BMI while being healthy, and it’s not designed for children, teens or pregnant women.
Frequently asked questions
What is a healthy BMI?
For most adults, 18.5 to 24.9.
Is BMI accurate?
It’s a useful screening tool but doesn’t account for muscle mass, age or body-fat distribution.
Can children use this BMI calculator?
No. Children and teens need BMI-for-age percentiles instead.