BMI Calculator ā Check Body Mass Index & Healthy Weight Range
Use this free BMI calculator to calculate body mass index with US, metric, or mixed units, and view your BMI category, healthy weight range, BMI Prime, and Ponderal Index.
BMI Calculator
Enter your age, gender, height, and weight to calculate BMI and related health indicators.
BMI Calculator
Result
BMI = 0 kg/mĀ² (Normal)
- Healthy BMI range: 18.5 kg/mĀ² - 25 kg/mĀ²
- Healthy weight for the height: --
- BMI Prime: --
- Ponderal Index: --
How to Use
- Select US Units, Metric Units, or Other Units.
- Enter your age, gender, height, and weight.
- Click Calculate to see your BMI result.
- Review your BMI category, healthy weight range, BMI Prime, and Ponderal Index.
How This Calculator Works
This BMI calculator converts your measurements into metric units and applies the standard BMI formula. It also estimates a healthy weight range for your height, plus BMI Prime and Ponderal Index.
Frequently Asked Questions
What is BMI?
BMI, or body mass index, is a measurement based on height and weight used as a general screening tool for weight status.
Is BMI always accurate?
BMI is useful as a general screening indicator, but it does not directly measure body fat or body composition.
What is BMI Prime?
BMI Prime is your BMI divided by 25 and helps show how your BMI compares to the upper end of the normal range.
The Body Mass Index (BMI) Calculator
The BMI Calculator can be used to calculate BMI value and corresponding weight status while taking age into consideration. Use the āMetric Unitsā tab for SI units or āOther Unitsā to convert mixed units. This calculator also computes BMI Prime and Ponderal Index.
BMI introduction
BMI is a measurement of leanness or corpulence based on height and weight. It is used as a general indicator for whether body weight is in a healthy range for height. BMI should be used as a screening indicator alongside other clinical measures.
BMI table for adults (WHO)
| Classification | BMI range - kg/mĀ² |
|---|---|
| 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 table for children and teens, age 2-20 (CDC)
| Category | Percentile Range |
|---|---|
| Underweight | <5% |
| Healthy weight | 5% - 85% |
| At risk of overweight | 85% - 95% |
| Overweight | >95% |
Risks associated with being overweight
- High blood pressure
- Higher LDL, lower HDL, and elevated triglycerides
- Type II diabetes, coronary heart disease, stroke
- Gallbladder disease and osteoarthritis
- Sleep apnea and breathing problems
- Certain cancers and lower quality of life
- Mental illness, pain, reduced physical function, and mortality risk
Risks associated with being underweight
- Malnutrition, vitamin deficiencies, anemia
- Osteoporosis and decreased immune function
- Growth/development issues in youth
- Potential reproductive issues and surgery complications
- Increased mortality risk and possible underlying illness
Limitations of BMI
BMI is only an estimate and does not directly measure body fat or body composition. Age, sex, ethnicity, muscle mass, and activity level can influence interpretation. For children/adolescents, growth and maturation add further complexity.
BMI formula
USC Units: BMI = 703 Ć mass(lb) / height(in)Ā²
SI Units: BMI = mass(kg) / height(m)Ā²
BMI Prime
BMI Prime = BMI / 25. Underweight < 0.74, Normal 0.74ā1, Overweight > 1, Obese > 1.2.
Ponderal Index
PI is similar to BMI but uses height cubed. SI form: PI = mass(kg) / height(m)Ā³. US form often shown as height(in) / āmass(lb).