BMI Calculator
Input Information
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Result
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What is BMI?
BMI (Body Mass Index) is an internationally recognized indicator for measuring human body fatness and health risks. It evaluates individual weight status through the ratio of weight to height, applicable to most adults. BMI calculation is simple and widely used in epidemiological surveys and clinical assessments.
- BMI mainly reflects total body fat content and cannot distinguish between fat and muscle.
- For special populations such as athletes, pregnant women, and the elderly, BMI is for reference only.
- Both high and low BMI may increase the risk of chronic diseases such as cardiovascular disease and diabetes.
BMI Calculation Formula
Metric Units
BMI=
Weight (kg)
Height (m)²
Example: Height 170cm, Weight 65kg
BMI = 65 ÷ (1.70)² = 65 ÷ 2.89 = 22.5
US Units
BMI=×703
Weight (lb)
Height (in)²
Example: Height 5'7", Weight 140lb
BMI = 140 ÷ (67)² × 703 = 140 ÷ 4489 × 703 = 22.0
Formula Notes
- • Metric units: weight in kilograms (kg), height in meters (m)
- • US units: weight in pounds (lb), height in inches (in), multiplied by conversion factor 703
- • BMI calculation results are for reference only. For specific health conditions, please consider body fat percentage, waist circumference and other indicators comprehensively.
Adult BMI Standards
| Category | BMI Range (kg/m²) |
|---|---|
| Severely Underweight | < 16.0 |
| Underweight | 16.0 - 18.4 |
| Normal | 18.5 - 24.9 |
| Overweight | 25.0 - 29.9 |
| Obese Class I | 30.0 - 34.9 |
| Obese Class II | 35.0 - 39.9 |
| Obese Class III | ≥ 40.0 |
* Reference World Health Organization (WHO) standards. Some Asian countries set the "normal" upper limit to 23.9.
Children and Adolescents BMI Standards
| Age | Underweight | Normal | Overweight | Obese |
|---|---|---|---|---|
| 7-9 | < 14.5 | 14.5-18.0 | 18.1-20.0 | ≥ 20.1 |
| 10-12 | < 15.5 | 15.5-19.0 | 19.1-22.0 | ≥ 22.1 |
| 13-15 | < 16.5 | 16.5-21.0 | 21.1-24.0 | ≥ 24.1 |
| 16-18 | < 17.5 | 17.5-23.0 | 23.1-26.0 | ≥ 26.1 |
* Reference Chinese Health Industry Standard "WS/T 586-2018".
BMI is for reference only. For specific health conditions, consult a professional doctor.