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What Is BMI? Body Mass Index Explained

WellnessCalcs Guide
Reviewed for clarity and educational use. Last updated 2026.

BMI, or body mass index, compares weight to height using a simple formula. It is often used as a quick screening tool for adults because it is easy to calculate and compare. However, BMI does not directly measure body fat or health.

Why BMI has limits

Athletes may have a high BMI because of muscle mass. Older adults may have body composition changes that BMI does not show. Pregnancy, fluid retention, and medical conditions can also affect interpretation.

How to use BMI wisely

BMI is best viewed as a starting point. It can be helpful when combined with waist measurement, lifestyle, blood pressure, labs, and professional guidance. Try our BMI calculator and compare it with other tools such as body fat percentage estimates.

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Disclaimer: This article is for general education only and does not replace advice from a qualified professional.