By /

🧮 BMI Calculator

ℹ️ Modify the values and click Calculate to get your BMI results

BMI Calculator

cm
kg

Results

BMI Result
BMI = 20.1 kg/m² (Normal)
BMI = 20.1
  • • 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
Health Advice:
Great! You have a healthy weight. Keep maintaining your current lifestyle.

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)

ClassificationBMI (kg/m²)
Severe Thinness< 16
Moderate Thinness16 – 17
Mild Thinness17 – 18.5
Normal18.5 – 25
Overweight25 – 30
Obese Class I30 – 35
Obese Class II35 – 40
Obese Class III> 40

BMI Categories for Children (CDC, age 2–20)

CategoryPercentile
Underweight< 5%
Healthy weight5% – 85%
At risk of overweight85% – 95%
Overweight> 95%

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

Related Calculators:
BMR Calculator, Calorie Calculator

External Resources:
BMI Calculator on Calculator.net