BMI Calculator
Calculate your Body Mass Index based on your height and weight.
Updated
<18.5Normal
18.5–24.9Overweight
25–29.9Obese
30+
What is BMI?
Body Mass Index (BMI) is a measure of body fat based on height and weight. It applies to adult men and women aged 20 and older. BMI is a screening tool — it doesn't diagnose body fatness or health conditions directly.
BMI Categories
| BMI | Category |
|---|---|
| < 18.5 | Underweight |
| 18.5 – 24.9 | Normal weight |
| 25.0 – 29.9 | Overweight |
| 30.0 – 34.9 | Obesity Class I |
| 35.0 – 39.9 | Obesity Class II |
| ≥ 40.0 | Obesity Class III |
BMI doesn't account for muscle mass, bone density, age, sex, or ethnicity. Athletes may have a high BMI due to muscle mass. Always consult a healthcare provider for a full health assessment.
Frequently Asked Questions
What is a healthy BMI?
For adults 20 and older, a BMI between 18.5 and 24.9 is classified as normal weight. Below 18.5 is underweight, 25–29.9 is overweight, and 30+ is obese.
Is BMI accurate for athletes?
Not always. BMI can't distinguish muscle from fat, so muscular people often score as overweight despite low body fat. Body fat percentage or waist measurements give a fuller picture.
Does BMI work the same for men and women?
The adult BMI formula and categories are identical for men and women. For children and teens, BMI is instead assessed as an age- and sex-specific percentile.
What is BMI Prime?
Your BMI divided by 25 (the upper healthy limit). A BMI Prime under 1.0 means you're within or below the healthy range; over 1.0 means above it.