BMI Calculator
Calculate your Body Mass Index (BMI) to understand your weight status. BMI is a measure of body fat based on height and weight.
Your Details
Enter your age, gender, height, and weight, then click Calculate to see your BMI assessment with detailed charts and guidance.
Your Body Mass Index
0.0
kg/m²
BMI Prime
0.00
Ponderal Index
0.0
Healthy Range
0 - 0 kg
Category
-
BMI Gauge
BMI Categories
Healthy Weight Range
BMI Scale
Complete User Guide
What is BMI?
Body Mass Index (BMI) is a measurement of a person's leanness or corpulence based on their height and weight, and is intended to quantify tissue mass. It is widely used as a general indicator of whether a person has a healthy body weight for their height.
BMI = Weight (kg) ÷ Height (m)²
These ranges of BMI vary based on factors such as region and age, and are sometimes further divided into subcategories such as severely underweight or very severely obese. Being overweight or underweight can have significant health effects.
BMI Categories
Underweight: BMI < 18.5
This range includes severe thinness (<16), moderate thinness (16-17), and mild thinness (17-18.5). You may need to gain weight. Consult with a healthcare provider.
Normal Weight: BMI 18.5-24.9
Congratulations! You are in a healthy weight range. Continue maintaining a balanced diet and regular physical activity.
Overweight: BMI 25-29.9
Consider a balanced diet and regular exercise. Small lifestyle changes can help you reach a healthy weight.
Obese: BMI ≥ 30
This includes Obese Class I (30-35), Class II (35-40), and Class III (>40). Consult with a healthcare provider for a weight management plan.
How to Use This Calculator
- Select your preferred unit system (Metric or Imperial)
- Enter your age and gender
- Enter your current height accurately
- Enter your current weight
- Click 'Calculate BMI' to see your results
- Review the charts and detailed assessment
- Read the comprehensive guide below for interpretation
Understanding Your Results
BMI Value
Your calculated BMI number. This value is used to categorize your weight status.
BMI Prime
The ratio of your measured BMI to the upper limit of normal BMI (25). Values less than 0.74 indicate underweight, 0.74-1.0 is normal, greater than 1.0 is overweight, and greater than 1.2 is obese.
Ponderal Index
Similar to BMI but uses height cubed instead of squared. More reliable for very tall or short individuals.
Healthy Weight Range
The weight range (BMI 18.5-24.9) considered healthy for your height. This helps you understand your target weight range.
Understanding the Charts
BMI Gauge Chart
A circular gauge showing your BMI value visually. The color corresponds to your category (blue for underweight, green for normal, yellow for overweight, red for obese).
BMI Categories Chart
A horizontal bar chart showing all BMI categories. Your current category is highlighted, making it easy to see where you fall on the spectrum.
Healthy Weight Range Chart
Shows your current weight compared to the healthy weight range for your height. Green bars indicate the healthy range, while your current weight is shown in a color matching your BMI category.
BMI Scale
A visual scale showing all BMI ranges with a marker indicating your current position. This provides a quick, at-a-glance understanding of your BMI status.
BMI Formula
The equations used for calculating BMI in the International System of Units (SI) and the US customary system (USC):
SI, Metric Units:
BMI = mass (kg) / height² (m)
USC Units:
BMI = 703 × mass (lbs) / height² (in)
BMI Table for Adults
This is the World Health Organization's (WHO) recommended body weight based on BMI values for adults. It is used for both men and women, age 20 or older.
| Classification | BMI Range - 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 |
Important Notes
- This calculator is for educational and informational purposes only. It is not a diagnostic tool.
- BMI does not account for muscle mass, bone density, or body composition. Athletes or individuals with high muscle mass may have higher BMIs that don't reflect excess fat.
- BMI is further influenced by factors such as age, sex, ethnicity, muscle mass, body fat, and activity level.
- If you're concerned about your weight or BMI, please consult with qualified healthcare professionals or registered dietitians.
Risks of Being Overweight
Being overweight increases the risk of:
- High blood pressure
- Type II diabetes
- Coronary heart disease
- Stroke
- Certain cancers
- Sleep apnea
Risks of Being Underweight
Being underweight has associated risks:
- Malnutrition and vitamin deficiencies
- Osteoporosis
- Decreased immune function
- Growth and development issues
- Reproductive issues
- Increased mortality risk