BMI Calculator
Enter your weight and height to calculate your Body Mass Index. See your BMI category on a color-coded scale and your healthy weight range. Supports imperial and metric units.
Free BMI Calculator
Body Mass Index (BMI) is a widely used screening tool that estimates body fat based on your weight and height. While it does not measure body fat directly, BMI correlates with more direct measures of body fat and is a useful starting point for understanding whether your weight falls within a healthy range.
How BMI Is Calculated
BMI is calculated by dividing your weight in kilograms by the square of your height in meters. For imperial units, the formula multiplies your weight in pounds by 703 and divides by the square of your height in inches. The result is a single number that corresponds to one of six categories: underweight (below 18.5), normal weight (18.5 to 24.9), overweight (25 to 29.9), and three classes of obesity (30 to 34.9, 35 to 39.9, and 40 or above).
BMI Limitations
BMI does not distinguish between muscle and fat. Athletes and people with higher muscle mass may have an elevated BMI without excess body fat. Similarly, older adults may have a normal BMI but carry more fat due to muscle loss. For a more complete picture of your health, consider combining BMI with waist circumference, body fat percentage, or other measurements.
Frequently Asked Questions
What is BMI?
BMI (Body Mass Index) is a simple measure that uses your weight and height to estimate whether you are underweight, normal weight, overweight, or obese. It is calculated by dividing your weight in kilograms by the square of your height in meters.
How is BMI calculated?
The BMI formula is weight in kilograms divided by height in meters squared (kg/m²). For imperial units, the formula is (weight in pounds × 703) ÷ (height in inches)². A BMI of 18.5 to 24.9 is considered normal weight.
What is a healthy BMI range?
A healthy BMI is generally between 18.5 and 24.9. Below 18.5 is underweight, 25 to 29.9 is overweight, and 30 or above is classified as obese. These ranges apply to adults over 20 years old.
Is BMI accurate for athletes?
BMI does not distinguish between muscle mass and fat mass, so highly muscular individuals may have a high BMI despite having low body fat. For athletes or very muscular people, body fat percentage or waist-to-hip ratio may be more accurate measures of health.
Is my data private?
Yes. This calculator runs entirely in your browser. Your weight, height, and BMI results are never sent to any server. There are no accounts, no tracking, and no data collection.