What is a BMI Calculator?

A BMI (Body Mass Index) calculator is a health assessment tool that calculates your body mass index based on your height and weight. BMI is a widely used screening tool to identify potential weight problems in adults. Our free BMI calculator provides instant results and helps you understand your health category and ideal weight range.

How to Use the BMI Calculator

1. Enter your height in centimeters or feet and inches
2. Enter your weight in kilograms or pounds
3. Optionally enter your age and gender for more accurate results
4. Click "Calculate BMI" to see your results
5. Review your BMI category and health recommendations

What is BMI?

Body Mass Index (BMI) is a measure of body fat based on height and weight that applies to adult men and women. It's calculated by dividing your weight in kilograms by your height in meters squared (kg/m²). BMI provides a simple numeric measure of a person's thickness or thinness.

BMI Formula

BMI Categories

Adult BMI Categories (WHO Standard)

• Underweight: BMI less than 18.5
• Normal weight: BMI 18.5 to 24.9
• Overweight: BMI 25 to 29.9
• Obesity Class I: BMI 30 to 34.9
• Obesity Class II: BMI 35 to 39.9
• Obesity Class III: BMI 40 or higher

BMI Interpretation

Normal Weight (BMI 18.5-24.9)

This range is associated with the lowest risk of health problems. People in this range generally have a healthy body weight relative to their height.

Overweight (BMI 25-29.9)

This range indicates excess body weight that may increase the risk of health problems such as heart disease, diabetes, and high blood pressure.

Obesity (BMI 30+)

This range significantly increases the risk of serious health conditions including heart disease, stroke, type 2 diabetes, and certain cancers.

BMI Limitations

While BMI is a useful screening tool, it has limitations:

• Muscle Mass: Doesn't distinguish between muscle and fat
• Age: May not be accurate for older adults
• Gender: Doesn't account for different body compositions
• Ethnicity: May not be accurate for all ethnic groups
• Body Composition: Doesn't measure body fat percentage

Who Should Use BMI?

• Adults 20+ years: Primary screening tool
• General population: Health assessment
• Healthcare providers: Clinical assessment
• Fitness enthusiasts: Progress tracking

BMI and Health Risks

Health Risks Associated with High BMI

• Heart disease and stroke
• Type 2 diabetes
• High blood pressure
• Certain cancers
• Sleep apnea
• Osteoarthritis

Health Risks Associated with Low BMI

• Malnutrition
• Weakened immune system
• Osteoporosis
• Anemia
• Fertility issues

Improving Your BMI

For Overweight/Obese Individuals

• Create a calorie deficit through diet and exercise
• Focus on whole, nutrient-dense foods
• Engage in regular physical activity
• Get adequate sleep
• Manage stress levels

For Underweight Individuals

• Increase calorie intake with healthy foods
• Focus on nutrient-dense, high-calorie foods
• Engage in strength training to build muscle
• Consult with a healthcare provider

Alternative Health Measurements

• Waist Circumference: Measures abdominal fat
• Body Fat Percentage: More accurate than BMI
• Waist-to-Hip Ratio: Assesses fat distribution
• Skinfold Measurements: Estimates body fat