BMI Calculator

Calculate your Body Mass Index and understand your health category

Unit System

Weight (kg)*

Enter your weight

Height (cm)*

Enter your height

Note: BMI is a screening tool and does not diagnose body fatness or health. Consult a healthcare provider for health assessments.

Understanding BMI (Body Mass Index)

What is BMI?

Body Mass Index (BMI) is a measure of body fat based on height and weight. It's used as a screening tool to identify whether a person is underweight, normal weight, overweight, or obese.

BMI Categories

Underweight: BMI less than 18.5
Normal weight: BMI 18.5 to 24.9
Overweight: BMI 25 to 29.9
Obese: BMI 30 or greater

Important Note

While BMI is a useful screening tool, it has limitations. It doesn't directly measure body fat and may not accurately reflect health for athletes, elderly individuals, or certain ethnic groups. Always consult with a healthcare provider for personalized health assessments.

Frequently Asked Questions

What is BMI (Body Mass Index)?

BMI is a screening number calculated from your height and weight that estimates how your weight compares to a healthy range. It is used by clinicians worldwide as a quick first-pass indicator of underweight, healthy weight, overweight, and obesity, but it is not a direct measure of body fat.

How is BMI calculated?

In metric units, BMI = weight in kilograms ÷ (height in meters)². In imperial units, BMI = (weight in pounds ÷ (height in inches)²) × 703. Our calculator handles both unit systems automatically.

What is a healthy BMI range?

For adults aged 20 and older, the WHO categories are: under 18.5 underweight, 18.5–24.9 healthy weight, 25.0–29.9 overweight, and 30.0 or above obese. These ranges are general guidelines and do not account for muscle mass, age, or ethnicity.

Is BMI accurate for athletes or muscular people?

BMI can mis-classify athletes and very muscular individuals as overweight or obese because muscle is denser than fat. If you have above-average muscle mass, complement BMI with measurements like body-fat percentage, waist circumference, or DEXA scans for a more accurate picture.

Does BMI work the same for men and women?

BMI uses the same formula and the same adult cut-off points for men and women. However, women on average carry a higher percentage of body fat than men at the same BMI, so context still matters when interpreting results.

What should I do if my BMI is in an unhealthy range?

BMI is just a starting point. Speak with a healthcare provider before making major changes. They can review your full health picture (waist size, blood pressure, blood sugar, family history) and help you set realistic goals for sustainable weight management.