⚖️ BMI Calculator
Calculate your Body Mass Index (BMI) to understand if you're at a healthy weight. Get your BMI score, category (underweight, normal, overweight, obese), and healthy weight range based on your height.
How This Calculator Works
BMI (Body Mass Index) is a screening tool that estimates body fat based on your height and weight. It's calculated using this formula:
BMI = weight (kg) / [height (m)]²
For imperial measurements: BMI = (weight in lbs × 703) / [height in inches]²
Your BMI result is compared against standard categories established by the World Health Organization (WHO) and Centers for Disease Control (CDC):
- Underweight: BMI less than 18.5
- Normal weight: BMI 18.5 to 24.9
- Overweight: BMI 25 to 29.9
- Obese: BMI 30 or greater
The calculator also shows your healthy weight range—the minimum and maximum weights that would put your BMI in the "normal" category for your height.
Example Calculation
Example: Adult at 5'10" weighing 180 lbs
Height: 5 feet 10 inches = 70 inches
Weight: 180 pounds
Calculation: (180 × 703) / (70 × 70) = 126,540 / 4,900 = 25.8 BMI
Category: Overweight (BMI 25-29.9)
Healthy Range: For someone 5'10", a healthy weight is approximately 129-174 lbs (BMI 18.5-24.9)
Interpretation: This person's BMI of 25.8 is just into the "overweight" range. Losing 6-7 pounds would bring them into the "normal weight" category.
Common Questions
Is BMI an accurate measure of health?
BMI is a useful screening tool but has limitations. It doesn't distinguish between muscle and fat, so athletes with high muscle mass may show as "overweight" despite being healthy. It also doesn't account for age, sex, ethnicity, or body composition. Use BMI as one indicator, but consult a doctor for a complete health assessment.
What if my BMI is in the "overweight" or "obese" range?
A high BMI indicates increased risk for heart disease, diabetes, and other conditions. Talk to your doctor about healthy weight loss strategies. Even a 5-10% weight reduction can significantly improve health markers. Use our Calorie Calculator to plan a sustainable deficit.
What if my BMI is "underweight"?
A BMI under 18.5 may indicate malnutrition, eating disorders, or other health issues. Consult a doctor or registered dietitian. Being underweight carries risks like weakened immune system, osteoporosis, and fertility problems.
Does BMI apply to children and teens?
This calculator is for adults 18+. Children and teens need age- and sex-specific BMI percentile charts because their body composition changes with growth. Consult a pediatrician for child BMI assessment.