Free BMI Calculator Online
Use our free BMI calculator to quickly determine your Body Mass Index. BMI is a widely used screening tool that measures body fat based on your height and weight. Simply enter your measurements to find out if you fall into the underweight, normal weight, overweight, or obese category.
How BMI Is Calculated
The BMI formula divides your weight by the square of your height:
- Metric: BMI = weight (kg) / height (m)2
- Imperial: BMI = (weight (lbs) / height (in)2) x 703
For example, a person weighing 70 kg with a height of 1.75 m would have a BMI of 70 / (1.75 x 1.75) = 22.9.
BMI Categories
- Underweight: BMI less than 18.5
- Normal weight: BMI 18.5 to 24.9
- Overweight: BMI 25 to 29.9
- Obese: BMI 30 or greater
Limitations of BMI
While BMI is a useful screening tool, it has limitations:
- It doesn't distinguish between muscle and fat mass
- Athletes may have high BMI due to muscle mass
- It doesn't account for age, sex, or ethnicity
- It doesn't measure body fat distribution
For a complete health assessment, consult with a healthcare professional.
Frequently Asked Questions
What is a healthy BMI? A healthy BMI is typically between 18.5 and 24.9. This range is associated with lower risk of weight-related health problems.
Is BMI accurate for everyone? BMI is a general indicator and may not be accurate for athletes, elderly individuals, pregnant women, or people with high muscle mass.
How often should I check my BMI? Checking your BMI monthly or quarterly can help you track your progress if you're working on weight management goals.
Can children use this calculator? This calculator is designed for adults. Children and teens should use age- and sex-specific BMI percentile charts.
What should I do if my BMI is too high or low? Consult a healthcare provider for personalized advice. They can recommend appropriate diet and exercise plans based on your individual needs.
Does BMI predict health outcomes? While BMI correlates with health risks like heart disease and diabetes, it's just one factor. Lifestyle, diet, and genetics also play important roles.