BMI Calculator
Body Mass Index (BMI) is a screening measure that relates your weight to your height using the formula weight (kg) divided by height squared (m²). This free calculator computes your BMI in metric or imperial units and shows which standard weight category (underweight, normal, overweight, or obese) your result falls into.
Your BMI
Enter your height and weight to see your BMI.
How to calculate your BMI
- Choose metric (kg, cm) or imperial (lb, ft/in) units.
- Enter your height and weight.
- Read your BMI value and weight category instantly, no button press needed.
- Compare your result against the standard categories: underweight (below 18.5), normal (18.5–24.9), overweight (25–29.9), and obese (30+).
Frequently Asked Questions
What is BMI and how is it calculated?
Body Mass Index (BMI) is a value calculated from a person's weight and height. The formula is BMI = weight(kg) / height²(m²). It's a screening tool to categorize individuals as underweight, normal weight, overweight, or obese based on weight relative to height.
What are the BMI categories?
Standard BMI categories are: Underweight (below 18.5), Normal weight (18.5-24.9), Overweight (25-29.9), and Obese (30 and above). The obesity category is further divided into Class I (30-34.9), Class II (35-39.9), and Class III (40 and above).
What are the limitations of BMI?
BMI doesn't distinguish between muscle and fat, so muscular individuals may be classified as overweight despite being healthy. It also doesn't account for age, gender, ethnicity, body fat distribution, or individual health issues. BMI should be just one of several health assessments.
Is BMI different for children and teens?
Yes, BMI for children and teens (ages 2-20) is age and gender-specific, often referred to as BMI-for-age. It's calculated the same way as adult BMI but interpreted using percentile rankings specific to age and gender rather than fixed categories.
When should I be concerned about my BMI?
BMI values significantly below 18.5 or above 30 generally warrant discussion with a healthcare provider. However, even BMI values in the normal range don't guarantee good health, and values outside the normal range don't necessarily indicate health problems. Always consult with a healthcare professional for personalized advice.
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