BMI Calculator
🧮 BMI Calculator
ℹ️ Modify the values and click Calculate to get your BMI results
BMI Calculator
Results
- • Healthy BMI range: 18.5 kg/m² - 25 kg/m²
- • Healthy weight for your height: 59.9 kg - 81.0 kg
- • BMI Prime: 0.8
BMI Calculator Overview
The Body Mass Index (BMI) Calculator helps determine your BMI value and corresponding weight category, while considering your age.
👉 Use:
Metric Units tab for kilograms, meters, etc.
Other Units tab to convert between US and metric units.
💡 This tool also calculates the Ponderal Index (PI) alongside BMI, both explained below.
What is BMI?
BMI is a measure of body fat based on your height and weight. It gives a general indication of whether you have a healthy weight for your height.
Your BMI value helps categorize you as:
Underweight
Normal weight
Overweight
Obese
⚠️ These categories vary by age, region, and other factors. Being outside a healthy BMI range can affect your health, so BMI is a useful screening tool to decide if further assessment is needed.
BMI Categories for Adults (WHO)
| Classification | BMI (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 Categories for Children (CDC, age 2–20)
| Category | Percentile |
|---|---|
| Underweight | < 5% |
| Healthy weight | 5% – 85% |
| At risk of overweight | 85% – 95% |
| Overweight | > 95% |
Health Risks of Being Overweight
Excess weight can raise the risk of:
High blood pressure
Bad cholesterol (high LDL, low HDL, high triglycerides)
Type 2 diabetes
Heart disease, stroke
Gallbladder disease
Joint issues (osteoarthritis)
Breathing problems (sleep apnea)
Some cancers (e.g. breast, colon)
Lower quality of life
Mental health issues (depression, anxiety)
Health Risks of Being Underweight
Underweight individuals may face:
Malnutrition, vitamin deficiencies
Weaker bones (osteoporosis)
Lower immunity
Growth problems (kids/teens)
Hormonal/reproductive issues (women)
Higher risk during surgeries
Higher mortality risk
BMI Limitations
BMI is a helpful guide but doesn’t account for:
Muscle vs fat (athletes may show as overweight)
Age (older adults usually have more fat than younger adults at same BMI)
Gender (women tend to have more body fat)
Ethnicity, fitness level
👉 In children, puberty and growth affect BMI accuracy. BMI works best as part of a broader health check.
How to Calculate BMI
Metric formula:
BMI = weight (kg) / height² (m²)
US formula:
BMI = 703 × weight (lbs) / height² (in²)
👉 Example (5’10”, 160 lbs):
BMI = 23.0
What is BMI Prime?
BMI Prime = BMI / 25
< 0.74 = underweight
0.74 – 1 = normal
1 = overweight
1.2 = obese
What is the Ponderal Index (PI)?
PI is similar to BMI but better for very tall or short people.
Formula:
PI = height (in) / ∛weight (lbs)
👉 Example (5’10”, 160 lbs):
PI = 12.9