BMI Calculator
Calculate your Body Mass Index
BMI Categories
Note: BMI is a general indicator and doesn't account for muscle mass, bone density, or body composition. Consult a healthcare professional for personalized advice.
Free Online BMI Calculator
Calculate your Body Mass Index (BMI) instantly with our free online BMI calculator. BMI is a widely used screening tool that measures body fat based on your height and weight. It provides a quick assessment of whether you're underweight, normal weight, overweight, or obese according to international health standards.
Our calculator supports both metric (kilograms/centimeters) and imperial (pounds/feet-inches) units, making it accessible for users worldwide. Simply enter your height and weight, and get your BMI score along with a detailed interpretation of what it means for your health.
While BMI is a useful indicator for the general population, it has limitations. It doesn't distinguish between muscle and fat mass, which means athletes with high muscle mass may have elevated BMI scores despite having low body fat. Similarly, elderly individuals may have normal BMI but carry excess fat. Always consult with a healthcare professional for a comprehensive health assessment.
How to Calculate Your BMI
Select Your Unit System
Choose between Metric (kg/cm) or Imperial (lb/ft) measurement systems.
Enter Your Height
Input your height in centimeters for metric, or feet and inches for imperial.
Enter Your Weight
Input your weight in kilograms for metric, or pounds for imperial.
Get Your Results
Click Calculate to see your BMI score, category, and health recommendations.
BMI Formula
BMI = weight (kg) / height (m)²
BMI = (weight (lb) × 703) / height (in)²
The calculation is the same regardless of unit system - we convert to metric internally.
Who Uses BMI Calculators?
Health-Conscious Individuals
Track your weight status and monitor changes over time as part of a healthy lifestyle routine.
Fitness Enthusiasts
Use BMI as one metric among many to gauge progress in weight management and fitness goals.
Healthcare Providers
Screen patients for potential weight-related health issues and track treatment progress.
Nutritionists & Dietitians
Assess clients initial health status and create personalized meal plans and nutrition guidance.
Insurance Companies
Evaluate applicants health risk profiles as part of underwriting processes for life insurance.
Researchers
Collect population-level data for epidemiological studies on obesity and related health conditions.
Frequently Asked Questions
What is a healthy BMI range?
A healthy BMI falls between 18.5 and 24.9. This range is associated with the lowest risk of weight-related health problems for most adults. However, optimal BMI can vary based on age, ethnicity, and individual health factors.
Is BMI accurate for athletes?
BMI may not be accurate for athletes or highly muscular individuals. Muscle weighs more than fat, so someone with significant muscle mass may have a high BMI despite having low body fat. Additional measures like body fat percentage are more useful for athletes.
Does BMI apply to children?
This calculator is designed for adults 18+. Children and teens require BMI-for-age percentile charts that account for growth patterns. Pediatric BMI interpretation differs significantly from adult standards.
What health risks are associated with high BMI?
Elevated BMI is associated with increased risk of type 2 diabetes, heart disease, high blood pressure, certain cancers, sleep apnea, and osteoarthritis. However, BMI is just one factor - overall health depends on diet, exercise, genetics, and other lifestyle factors.
Can BMI be too low?
Yes, a BMI below 18.5 is considered underweight and can indicate malnutrition, eating disorders, or underlying health conditions. Low BMI is associated with weakened immune function, osteoporosis, and fertility issues.
How often should I check my BMI?
For most adults, checking BMI monthly or quarterly is sufficient unless actively working on weight management. Focus on long-term trends rather than daily fluctuations, which can be affected by hydration, meals, and other temporary factors.