Plain DatesClear date calculations, with the rules shown.

Age calculator

Calculate age from a birth date

Find completed years of age on a chosen date, the weekday of birth, and the next birthday under a stated leap-day rule.

Enter the dates

How age is calculated

The calculator first finds the latest birthday anniversary that is not later than the “age on” date. The number of completed anniversaries is the age in years. It also reports days since that anniversary and the next one.

Leap-day birthdays

For a person born February 29, 2000, the displayed 2025 anniversary is February 28. This is a transparent product convention, not a statement about legal adulthood, eligibility, or benefit rules.

Appropriate use

Use this page for ordinary calendar questions. Do not use it as medical advice or as the sole basis for legal, insurance, school, employment, or government eligibility decisions.

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