BMI Calculator 2025 - Free Body Mass Index Calculator
Calculate your Body Mass Index (BMI) instantly with our free online calculator. Get accurate BMI results, weight category classification, and personalized health recommendations based on World Health Organization (WHO) standards.
Understanding Body Mass Index (BMI)
What is BMI?
Body Mass Index (BMI) is a simple calculation using a person's height and weight. The BMI formula divides an adult's weight in kilograms by their height in meters squared. It's widely used as a screening tool to categorize individuals into weight categories.
BMI Formula:
BMI = weight (kg) ÷ height² (m²)
or BMI = (weight (lbs) ÷ height² (inches²)) × 703
BMI Categories
BMI Limitations
While BMI is a useful screening tool, it has limitations and doesn't directly measure body fat or overall health:
BMI may not be accurate for:
- • Athletes with high muscle mass
- • Pregnant or breastfeeding women
- • Elderly individuals with muscle loss
- • Children and adolescents
- • People with certain medical conditions
Additional factors to consider:
- • Waist circumference
- • Body fat percentage
- • Muscle mass distribution
- • Overall fitness level
- • Family history and genetics
Frequently Asked Questions
Is BMI accurate for everyone?
BMI is a general screening tool and may not be accurate for athletes, bodybuilders, pregnant women, or elderly individuals. It doesn't distinguish between muscle and fat mass. Consult with a healthcare provider for a comprehensive health assessment.
What's a healthy BMI range?
According to the World Health Organization, a BMI between 18.5 and 24.9 is considered normal weight. However, the ideal BMI can vary based on individual factors like age, ethnicity, and body composition.
How often should I check my BMI?
For most adults, checking BMI monthly or quarterly is sufficient for monitoring weight trends. If you're actively trying to lose or gain weight, weekly measurements can help track progress. Always measure at the same time of day for consistency.
Can BMI predict health risks?
BMI can indicate increased risk for certain health conditions like heart disease, diabetes, and high blood pressure. However, it's just one factor. Other measurements like waist circumference, blood pressure, and cholesterol levels provide a more complete health picture.