Plain Date Tools

Date Calculator

Move a date forward or backward using ordinary calendar units. The calculator shows the resulting date and weekday.

What would you like to do?
Date format

Enter dates with hyphens in the selected format.

Unit

Calendar behavior

This tool uses calendar days, weeks, months, and years. When an operation reaches a shorter month, it uses that month’s last valid day—for example, one month after January 31 is February 28 or 29.

It uses the Gregorian calendar only. It does not account for business days, holidays, or local deadline rules. Verify any legal or contractual deadline independently.