What is a normal BMI?

A normal BMI is between 18.5 and 24.9. This range is considered healthy for most adults and is associated with the lowest risk of weight-related diseases.

Is BMI accurate for athletes?

BMI can be misleading for athletes because it doesn't distinguish between muscle and fat. A muscular person may have a "overweight" BMI despite having low body fat. Body fat percentage is a better measure for athletes.

Blog/Health

Health · 5 min read

What is BMI? Understanding Body Mass Index, Charts & Healthy Ranges

Body Mass Index (BMI) is a number calculated from your height and weight that provides a rough estimate of body fat. It's used worldwide by doctors as a quick screening tool — not a diagnosis, but a starting point for understanding weight-related health risks.

The BMI Formula

BMI is calculated with a simple formula:

BMI = weight (kg) / height (m)²

For imperial units: BMI = (weight in lbs × 703) / (height in inches)². For example, a person who weighs 70 kg and is 1.75 m tall has a BMI of 70 / (1.75 × 1.75) = 22.9.

BMI Categories

The World Health Organization (WHO) defines these BMI categories for adults:

Underweight: Below 18.5
Normal weight: 18.5 – 24.9
Overweight: 25 – 29.9
Obese Class I: 30 – 34.9
Obese Class II: 35 – 39.9
Obese Class III: 40 and above

BMI Differences: Men vs Women

While the BMI formula is the same for everyone, body composition differs between men and women. Women naturally carry more body fat, while men tend to have more muscle mass. A woman and man with the same BMI may have very different body fat percentages. This is why BMI should be used alongside other measures like waist circumference.

Limitations of BMI

BMI is a useful screening tool, but it has limitations. It doesn't account for muscle mass, bone density, age, or fat distribution. Athletes may be classified as "overweight" despite being in excellent shape. Older adults may have a "normal" BMI but carry excess body fat.

For a more complete picture, combine BMI with waist circumference, body fat percentage, and advice from a healthcare professional.

Calculate Your BMI

Use our free BMI calculator to find your Body Mass Index instantly. It supports both metric and imperial units and provides gender-specific health tips.