Add to a Date

Add a number of years, months, weeks, and days to a starting date and get the resulting date with its day of the week.

About Add to a Date

Date arithmetic moves a calendar date forward or back by a set period. This calculator applies years, months, weeks (as 7 days each), and days in a single step, then normalizes the result to a real calendar date. If the target month is too short for the day number, the extra days roll into the next month. It shows the result in long form, in ISO format (YYYY-MM-DD), and as a number of days from the start.

How to use Add to a Date

Fill in "Start date", "Operation", "Years" and "Months", and the other options.
The result appears below and updates as you type.
Copy the result with the copy button, or download it as a file where that is offered.

Questions about Add to a Date

What is one month after January 31?

February has no 31st, so the extra days roll over: the result is March 3, or March 2 in a leap year. If you need the last day of February, subtract the overflow days manually.

Runs in your browser. Page last updated November 12, 2026.

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