BMI Calculator
Enter your height and weight to instantly calculate your Body Mass Index — with context to help you understand what it means.
| Underweight | Below 18.5 |
| Normal weight | 18.5 – 24.9 |
| Overweight | 25.0 – 29.9 |
| Obese Class I | 30.0 – 34.9 |
| Obese Class II+ | 35.0 and above |
What is BMI?
Body Mass Index (BMI) is a widely used screening tool that estimates whether a person's weight is appropriate for their height. It was developed by Belgian mathematician Adolphe Quetelet in the 19th century and is now used by healthcare providers worldwide as a quick, cost-free initial assessment.
BMI is calculated by dividing your weight in kilograms by the square of your height in meters: BMI = kg / m². The result falls into one of several categories defined by the World Health Organization (WHO).
Limitations of BMI
While BMI is useful as a population-level screening tool, it has important limitations. It does not directly measure body fat, and two people with the same BMI can have very different body compositions. Athletes often have a high BMI due to muscle mass, not excess fat. Similarly, BMI may underestimate health risk in older adults who have lost muscle mass.
BMI also does not account for where fat is distributed in the body — waist circumference is often a better predictor of metabolic risk.
What should I do with my result?
Use your BMI as a starting point for a conversation with your healthcare provider, not as a definitive diagnosis. If your BMI falls outside the normal range, consider also tracking waist circumference, reviewing your eating patterns, and consulting a registered dietitian or doctor for personalized guidance.