Understanding Body Mass Index (BMI)
Our BMI calculator helps you determine your Body Mass Index, a widely used measure to assess whether your weight is in a healthy range for your height. Understand your BMI category and what it means for your health.
What is BMI?
BMI (Body Mass Index) is a measure of body fat based on height and weight that applies to adult men and women. It's calculated by dividing your weight in kilograms by your height in meters squared. While not a direct measure of body fat, BMI is a useful screening tool for weight categories.
BMI Calculation Formula
BMI = weight (kg) / height (m)². For imperial units: BMI = (weight in pounds × 703) / (height in inches)².
Example:
For a person 5'10" (70 inches) weighing 165 lbs: BMI = (165 × 703) / (70)² = 115,995 / 4,900 = 23.7 (normal weight).
Common Use Cases
Real-world applications for this calculator
Health Screening
Quickly assess whether your weight falls within a healthy range for your height.
Weight Goals
Determine a target weight range based on healthy BMI values for your height.
Health Monitoring
Track changes in your BMI over time as part of a health and fitness program.
Tips
- BMI is one tool-also consider waist circumference and overall fitness.
- Athletes and muscular individuals may have a high BMI despite being healthy.
- BMI thresholds may differ for certain ethnic groups.
- Focus on overall health trends, not just a single number.
Frequently Asked Questions
What is a healthy BMI range?
A healthy BMI is typically between 18.5 and 24.9. Underweight is below 18.5, overweight is 25-29.9, and obese is 30 or higher. However, BMI doesn't account for muscle mass, age, or body composition.
How accurate is BMI?
BMI is a useful screening tool but not a diagnostic measure. It may overestimate body fat in athletes with high muscle mass and underestimate it in older adults who have lost muscle. Use it alongside other health indicators.
Does BMI apply to children?
Children and teens use BMI-for-age percentiles, which compare a child's BMI to others of the same age and sex. Adult BMI categories don't apply to those under 20.
What weight should I be for my height?
For a healthy BMI (18.5-24.9), calculate: minimum weight = 18.5 × (height in m)², maximum = 24.9 × (height in m)². For someone 5'8" (1.73m), healthy weight is roughly 55-75 kg (121-165 lbs).
Why might BMI be misleading?
BMI doesn't distinguish between fat and muscle, doesn't consider fat distribution, and varies by ethnicity. Athletes may have high BMI but low body fat. It's best used with other measures like waist circumference.