BMI Calculator
Calculate your Body Mass Index and see where you stand on the scale.
Free Online BMI Calculator
The Toolts BMI Calculator quickly estimates your Body Mass Index using either metric or imperial measurements. BMI is a widely used screening tool that estimates body fat based on the relationship between your weight and height. While not a diagnostic measure, it provides a useful starting point for understanding whether your weight falls within a healthy range.
How BMI Is Calculated
The BMI formula divides your weight by the square of your height. In metric units: BMI = weight (kg) ÷ height (m)². In imperial units: BMI = (weight (lbs) × 703) ÷ height (inches)². The result is a single number that falls on a standardized scale used by healthcare organizations worldwide.
BMI Categories
The World Health Organization classifies BMI into four main categories. A BMI below 18.5 is considered underweight. A BMI of 18.5 to 24.9 is normal weight. A BMI of 25 to 29.9 is overweight. A BMI of 30 or higher is classified as obese, with further subdivisions at 35 (Class II) and 40 (Class III). These thresholds are based on population-level health risk data.
Limitations of BMI
BMI does not distinguish between muscle and fat, so athletes or people with high muscle mass may be classified as overweight despite having low body fat. It also does not account for body fat distribution — visceral fat around the waist carries greater health risks than subcutaneous fat elsewhere. Age, sex, and ethnicity can also affect how BMI relates to actual health risk. For a more complete picture, consider consulting with a healthcare provider who can evaluate additional factors like waist circumference, blood pressure, and cholesterol levels.