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Is the age you turn on your birthday the age you completed?

According to the Centers for Disease Control and Prevention (CDC), the standard measure of age, known as chronological age, is calculated as the age at your last birthday. This means that, yes, the age you turn on your birthday is the age you have completed, not the age you are beginning. While this might seem counterintuitive to some, it aligns with how we mark the full passage of a year.