Date math
Date Calculator Online
Use this date calculator online to add or subtract days, weeks, months or years from any date. It is useful for schedules, deadlines, project plans and holiday preparation.
- Add or subtract time from a chosen base date.
- See the resulting weekday and day-of-year instantly.
- Helpful for countdown planning, deadlines and milestones.
Date Calculator Tool
Choose a base date, enter an amount and decide whether to add or subtract time.
Choose a date and amount to calculate a new date.
How to Use It
Select a base date
Start with the date you already know, such as an event date or deadline.
Add or subtract time
Choose the amount and the unit, then decide whether to move forward or backward in time.
Review the result
The tool returns the resulting date along with the weekday and day-of-year for extra context.
FAQ
Can I add weeks or months?
Yes. You can add or subtract days, weeks, months or years.
Is this date calculator free?
Yes. It is free to use online.
Can I use it on mobile?
Yes. It works on modern mobile browsers.
Can I use it for project planning?
Yes. It is useful for schedules, deadlines, launches and preparation periods.