BMI Calculator | Calculate Body Mass Index
Free online BMI (Body Mass Index) calculator. Calculate your BMI instantly and understand what it means for your health. Available in metric and imperial units.
Calculate Your BMI
BMI Classifications for Adults
| Classification | BMI Range (kg/m²) |
|---|---|
| Severe Thinness | < 16 |
| Moderate Thinness | 16 - 17 |
| Mild Thinness | 17 - 18.5 |
| Normal | 18.5 - 25 |
| Overweight | 25 - 30 |
| Obese Class I | 30 - 35 |
| Obese Class II | 35 - 40 |
| Obese Class III | > 40 |
BMI for Children and Teens (2-20 years)
| Category | Percentile Range |
|---|---|
| Underweight | < 5% |
| Healthy weight | 5% - 85% |
| At risk of overweight | 85% - 95% |
| Overweight | > 95% |
BMI Formulas
Metric Formula
Imperial Formula
BMI Prime Classifications
| Classification | BMI | BMI Prime |
|---|---|---|
| Severe Thinness | < 16 | < 0.64 |
| Moderate Thinness | 16 - 17 | 0.64 - 0.68 |
| Mild Thinness | 17 - 18.5 | 0.68 - 0.74 |
| Normal | 18.5 - 25 | 0.74 - 1 |
| Overweight | 25 - 30 | 1 - 1.2 |
| Obese Class I | 30 - 35 | 1.2 - 1.4 |
| Obese Class II | 35 - 40 | 1.4 - 1.6 |
| Obese Class III | > 40 | > 1.6 |
BMI Formula
Metric Formula
BMI = weight(kg) / height(m)²
Imperial Formula
BMI = 703 × weight(lb) / height(in)²
BMI Categories
Underweight
May indicate nutritional deficiency or other health issues. Consult with healthcare provider.
Normal Weight
Generally indicates a healthy weight for most adults.
Overweight
May increase risk of health issues. Consider lifestyle modifications.
Obese
Increased risk of several health conditions. Consult healthcare provider.
Frequently Asked Questions
What is BMI?
Body Mass Index (BMI) is a simple measurement using your weight and height to work out if your weight is healthy.
How accurate is BMI?
BMI is a useful indicator of healthy weight for most adults, but it doesn't account for factors like muscle mass, bone density, age, and sex.
How often should I check my BMI?
It's recommended to check your BMI when there are significant changes in your weight or every 6-12 months as part of regular health monitoring.
BMI Calculators
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About this Calculator
Free online BMI (Body Mass Index) calculator. Calculate your BMI instantly and understand what it means for your health. Available in metric and imperial units.