BMI Calculator
Calculate your Body Mass Index and see where you fall on the BMI scale.
Your BMI
22.9
Normal
Understanding Body Mass Index (BMI)
Body Mass Index (BMI) is a simple screening tool that estimates body fat based on a person's weight and height. It was developed by Belgian mathematician Adolphe Quetelet in the 1830s and remains one of the most widely used methods for categorizing weight status in adults. The formula divides weight in kilograms by height in meters squared (kg/m²).
BMI is used by healthcare professionals worldwide as a quick screening tool to identify potential weight problems in adults. The World Health Organization (WHO) defines four main categories: underweight (BMI below 18.5), normal weight (18.5 to 24.9), overweight (25 to 29.9), and obese (30 and above). These categories are associated with different levels of health risk.
While BMI is a useful starting point, it has important limitations. It does not distinguish between muscle mass and fat mass, which means that athletes and very muscular individuals may have a high BMI despite having low body fat. Similarly, older adults may have a normal BMI but carry excess fat. BMI also does not account for fat distribution; abdominal fat carries more health risk than fat stored in other areas.
Despite its limitations, BMI remains valuable as a population-level health indicator and a personal screening tool. For most adults, BMI provides a reasonable estimate of weight status and associated health risks. For a more complete picture, healthcare professionals often combine BMI with other measurements such as waist circumference, body fat percentage, and blood work.
When to Use This Calculator
- General health screening: get a quick estimate of your weight category
- Fitness tracking: monitor changes in your BMI over time as part of a health plan
- Medical preparation: know your BMI before a doctor's appointment or health screening
- Research: understand BMI ranges for health education and wellness programs
- Goal setting: use BMI categories as a reference point for weight management goals
Health Tips
- ✓BMI is a screening tool, not a diagnosis; always consult a healthcare professional for health advice
- ✓Track your BMI over time rather than focusing on a single measurement
- ✓Combine BMI with waist circumference for a better picture of health risk
- ✓Remember that BMI does not account for muscle mass; athletes may have a higher BMI without excess fat
- ✓Focus on overall health habits (nutrition, exercise, sleep) rather than just a number on the scale
Frequently Asked Questions
What is BMI and how is it calculated?
BMI (Body Mass Index) is a measure of body fat based on height and weight. It is calculated by dividing your weight in kilograms by your height in meters squared (kg/m²). For example, a person who is 1.75m tall and weighs 70kg has a BMI of 22.9 (70 / 1.75²).
What are the BMI categories?
The standard BMI categories defined by the WHO are: Underweight (below 18.5), Normal weight (18.5 to 24.9), Overweight (25 to 29.9), and Obese (30 and above). These ranges apply to adults aged 20 and older.
Is BMI an accurate measure of health?
BMI is a useful screening tool but has limitations. It does not distinguish between muscle and fat, so athletes may have a high BMI despite being healthy. It also does not account for age, sex, bone density, or fat distribution. Consult a healthcare provider for a complete health assessment.
What is a healthy BMI range?
A healthy BMI is generally between 18.5 and 24.9. This range is associated with the lowest risk of weight-related health problems. However, optimal BMI can vary based on individual factors like age, sex, ethnicity, and muscle mass.