Body Mass Index (BMI) Calculator (USA)
Calculate your Body Mass Index (BMI) using your weight and height. BMI is a measure of body fat based on height and weight.
How to Calculate BMI
Body Mass Index is calculated using weight and height:
Or using US customary units:
- Formula: BMI = weight (kg) / (height (m) ^ 2)
- Inputs: Weight in kg, Height in meters
- Output: BMI value
BMI Calculator
BMI Breakdown
BMI Calculation Details
BMI Categories
Health Recommendations
Based on your BMI classification:
- Maintain current healthy weight with balanced diet
- Engage in regular physical activity (150 min/week)
- Monitor weight changes periodically
- Continue healthy eating habits
- BMI is a screening tool but does not diagnose body fatness or health
- Muscle mass, bone density, and overall body composition affect BMI
- Consult a healthcare professional for comprehensive health assessment
- BMI may not accurately reflect health risks for all populations
Q&A
Q: What are the limitations of using BMI as a health indicator?
A: While BMI is widely used, it has several important limitations:
Body Composition:
- Muscle vs. Fat: BMI cannot distinguish between muscle and fat mass
- Athletes: May be classified as overweight despite low body fat
- Elderly: May appear normal despite high body fat percentage
Population Differences:
- Ethnicity: Different ethnic groups have varying health risks at similar BMIs
- Gender: Women typically have higher body fat percentages than men at same BMI
- Age: BMI cutoffs may not reflect risks for older adults
Health Assessment:
- Metabolic Health: Some with normal BMI have metabolic issues
- Distribution: Visceral fat (abdominal) is more harmful than subcutaneous fat
- Other Indicators: Waist circumference, body fat percentage are better predictors
For a complete health picture, combine BMI with other measures like waist circumference, blood pressure, and metabolic markers.
Q: I'm very muscular but my BMI says I'm overweight. Is this accurate?
A: This is a common issue with BMI for muscular individuals. Here's why:
Muscle vs. Fat Density:
- Muscle is denser: Muscle weighs about 18% more than fat per unit volume
- BMI limitation: Cannot differentiate between muscle and fat mass
- Result: Muscular individuals often fall into overweight category despite being lean
Alternative Measures:
- Body Fat Percentage: More accurate indicator of leanness
- Waist Circumference: Better predictor of health risks
- DEXA Scan: Gold standard for body composition
- Waist-to-Hip Ratio: Indicates fat distribution pattern
If you're muscular and fit, your BMI classification may not accurately reflect your health status. Focus on body composition metrics rather than BMI alone.