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Calculating exact age is more complex than subtracting birth year from the current year. Months have different lengths (28, 29, 30, or 31 days), and leap years add an extra day every four years. A precise age calculator accounts for all of these by counting calendar months and remaining days individually rather than dividing by a fixed number.

For example, someone born on January 31 turning one month older doesn't land on February 31 — that date doesn't exist. A proper calculator handles this by rolling to the last valid day of the shorter month. The same logic applies across leap year boundaries: a birthday on February 29 needs special handling in non-leap years. These edge cases are why simple year subtraction often gives an incorrect age by a day or more.

Birthdays44 handles all of this automatically — try it free on iOS & Android →