BMI Health Calculator
Body Mass Index (BMI) is a simple calculation using your height and weight to assess your body composition. While not a direct measure of body fat, it helps identify potential weight-related health risks. Remember, BMI is just one indicator – consult a healthcare professional for a comprehensive health assessment.
About the BMI Meter: The meter below visually represents the BMI categories.
The blue section indicates underweight, green shows healthy range, yellow is overweight,
and red represents obesity. Your result will be marked with a triangle indicator on this scale.
Metric
US Units
Other
ages: 2 – 120
Your BMI: 20.1 kg/m²
Normal Weight
16
17
18.5
25
30
35
40
Underweight
Normal
Overweight
Obese
Your BMI Value:
20.1
Healthy BMI Range:
18.5 – 25 kg/m²
Healthy Weight Range:
59.9 – 81 kg
BMI Prime:
0.8
Ponderal Index:
11.1 kg/m³
Health Tip: Maintaining a normal BMI reduces your risk for heart disease, diabetes, and other chronic conditions.
Focus on balanced nutrition and regular physical activity for long-term health benefits.
BMI Overview
- BMI is a numerical value derived from a person’s height and weight.
- It estimates body fat and categorizes body weight status.
- It helps assess if someone is underweight, normal, overweight, or obese.
BMI Categories for Adults (WHO Standard)
- 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 & Teens (Ages 2–20, CDC)
- Underweight: < 5th percentile
- Healthy Weight: 5th – 85th percentile
- At Risk of Overweight: 85th – 95th percentile
- Overweight: > 95th percentile
Health Risks – Overweight
- Heart disease, stroke, type 2 diabetes
- High blood pressure, cholesterol issues
- Sleep apnea, joint problems
- Some cancers, mental health issues
- Lower quality of life and increased mortality risk
Health Risks – Underweight
- Malnutrition, anemia, osteoporosis
- Weak immune function
- Growth and reproductive issues
- Higher surgical complications
- Increased mortality risk
BMI Limitations
- Doesn’t measure fat directly or reflect body composition.
- Not accurate for muscular individuals or older adults.
- May misclassify based on age, sex, or ethnicity.
- Less reliable for very tall or short individuals.
BMI Formula
- US Units: BMI = 703 × (weight in lbs) / (height in inches)²
- Metric Units: BMI = (weight in kg) / (height in meters)²
BMI Prime
- Ratio of actual BMI to the upper limit of normal (25 kg/m²).
- Helps compare body weight status across populations.
- BMI Prime Formula: BMI / 25
Ponderal Index (PI)
- Alternative to BMI, better for extreme heights.
- Formula (US): Height (in) / ∛Weight (lbs)
- Formula (Metric): Weight (kg) / Height³ (m)