BMI Calculator
Calculate your Body Mass Index (BMI) and discover your healthy weight range
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Your Results
BMI Scale
What is BMI (Body Mass Index)?
Body Mass Index (BMI) is a simple calculation using a person's height and weight. The formula is BMI = kg/m² where kg is a person's weight in kilograms and m² is their height in metres squared. A BMI of 25.0 or more is overweight, while the healthy range is 18.5 to 24.9.
How to Use the BMI Calculator
- Choose your unit system: Select either Metric (kg, cm) or Imperial (lbs, inches)
- Enter your age: Your age helps provide context for your BMI results
- Select your gender: Gender affects ideal weight ranges
- Input your height: Enter your height in centimeters or feet and inches
- Input your weight: Enter your current weight in kilograms or pounds
- Calculate: Click the Calculate BMI button to see your results
Understanding Your BMI Results
BMI Categories
- Underweight (BMI < 18.5): May indicate malnutrition, eating disorder, or other health problems. Consult a healthcare provider.
- Normal weight (BMI 18.5-24.9): Indicates a healthy weight range for most adults. Maintain through balanced diet and exercise.
- Overweight (BMI 25-29.9): Higher than ideal weight. May increase risk of health problems. Consider lifestyle changes.
- Obese (BMI ≥ 30): Significantly elevated health risks. Medical consultation recommended for weight management plan.
BMI Formula
The BMI calculation uses the following formulas:
Metric: BMI = weight(kg) / [height(m)]²
Imperial: BMI = [weight(lbs) / height(in)²] × 703
Limitations of BMI
While BMI is a useful screening tool, it has limitations:
- Doesn't measure body fat directly: Two people with same BMI can have very different body compositions
- Doesn't account for muscle mass: Athletes may have high BMI due to muscle, not fat
- Age differences: Older adults naturally have more body fat than younger adults at same BMI
- Gender differences: Women typically have more body fat than men at same BMI
- Ethnicity variations: Health risks associated with BMI vary across different ethnic groups
Tips for Healthy Weight Management
- Eat a balanced diet: Focus on whole foods, fruits, vegetables, lean proteins, and whole grains
- Exercise regularly: Aim for 150 minutes of moderate aerobic activity per week
- Stay hydrated: Drink plenty of water throughout the day
- Get enough sleep: 7-9 hours per night supports healthy metabolism
- Manage stress: High stress can lead to weight gain
- Monitor progress: Track your weight and measurements regularly
- Be patient: Healthy weight loss is 1-2 pounds per week
When to Seek Medical Advice
Consult a healthcare professional if:
- Your BMI is below 18.5 or above 30
- You're experiencing rapid weight loss or gain
- You have concerns about your weight or health
- You're planning significant dietary or exercise changes
- You have existing health conditions affected by weight
Frequently Asked Questions
Is BMI accurate for everyone?
BMI is a general screening tool and may not be accurate for athletes, bodybuilders, pregnant women, elderly individuals, or certain ethnic groups. It should be used alongside other health assessments.
What is a healthy BMI?
For most adults, a BMI between 18.5 and 24.9 is considered healthy. However, this range may vary based on age, gender, and ethnicity.
How often should I check my BMI?
Checking your BMI monthly or quarterly is sufficient for most people. Focus more on consistent healthy habits than frequent measurements.
Can children use BMI calculators?
Children and teens need specialized BMI-for-age percentile calculations. Use a pediatric BMI calculator or consult with a pediatrician.