Age Calculator
Calculate completed age, exact calendar age, days lived, and the next birthday.
Calculate exact age from a birth date.
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If the target month is shorter, the result uses its last valid day. Years and months are applied before weeks and days.
Age is based on completed Gregorian calendar years, months, and days.
Result
- Total days
- Calendar difference
- Weeks and days
- D-Day
- Resulting date
- Completed age
- Exact age
- Total days lived
- Next birthday
How to use Age Calculator
Choose Date difference for days or a D-Day count, Add / subtract to move a calendar date, or Age for completed years and the next birthday. Calculations use date-only Gregorian calendar values, so daylight-saving time does not shift the answer.
Private, local processing
Your input and results are not uploaded or stored. They remain in this browser tab.
Frequently asked questions
Are the start and end dates both counted?
By default, the calculator counts the gap between the dates. Turn on Include the end date when a stay, event, or other period should count its final calendar day as well.
How are age and leap-day birthdays calculated?
Age means completed calendar years on the chosen reference date. A February 29 birthday is observed on February 28 in a non-leap year here; official rules can differ by jurisdiction, so verify legal deadlines separately.
Are my dates uploaded or saved?
No. Dates and results stay in this browser tab and are neither uploaded nor stored by the tool.