BMI Calculator
Calculate your Body Mass Index instantly using height and weight.
Frequently Asked Questions
What is a normal BMI range?
A BMI between 18.5 and 24.9 is considered normal.
Is BMI accurate?
BMI is a screening tool, not diagnostic.
How do thresholds differ for Asian adults?
Overweight starts at 23.0 (vs 25.0).
What is BMI Prime?
Ratio of your BMI to 25.0.
Can I use this for children?
Use CDC percentiles for ages 2-19.
BMI Calculator
Metric · Imperial
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Quick Reference
The Formula
BMI is a screening index computed from weight and height to categorize adults into weight categories.
Variable Definitions
Body Mass Index
A ratio of weight to height squared.
Healthy Weight Range
BMI 18.5–24.9 for your height.
Devine Formula
Male: 50 kg + 2.3 kg per inch over 5 ft.
How to Use This Calculator
Select Imperial or Metric.
Enter your height.
Enter your weight.
Review your BMI score and gauge.
BMI Classification Reference
| Category | BMI Range | Health risk |
|---|---|---|
| Severely Underweight | < 16.0 | High risk — malnutrition |
| Underweight | 16.0 – 18.4 | Moderate risk |
| Normal weight | 18.5 – 24.9 | Minimal risk |
| Overweight | 25.0 – 29.9 | Low–moderate risk |
| Obese Class I | 30.0 – 34.9 | Moderate risk |
| Obese Class II | 35.0 – 39.9 | High risk |
| Obese Class III | ≥ 40.0 | Very high risk |
Source: WHO BMI Classification, 2004.
Common Applications
- Health screening — primary care visits use BMI as an initial metabolic health indicator.
- Insurance underwriting — premiums use BMI categories in risk assessment.
- Clinical weight management — track BMI changes over time.
- Population health studies — agencies use BMI distributions to track obesity rates.
- Fitness goal setting — establish baseline BMI and monitor changes.
Understanding the Concept
BMI correlates with body fat at the population level. However, it cannot distinguish muscle from fat, does not account for fat distribution, and varies across ethnicities. Athletes may register as overweight despite low body fat. For Asian populations, the WHO recommends lower cutoffs (overweight at 23 instead of 25).
Sources & References
Super clean. Love the gauge.
Finally explains the limitations clearly.
Great metric/imperial switch.