How this calculation works
Find the calendar date a fixed number of days before or after a starting date. Enter a positive day offset to move forward or a negative offset to move backward. This is the quick day-count tool; use Date Add/Subtract when your instruction is expressed in calendar months or years instead.
Resulting date = starting date + signed whole-day offset. Offset zero returns the starting date; every calendar day, including weekends and leap days, counts.
Worked example
This example uses illustrative inputs. Your current result is shown above.
Start on 1 January 2024 and add 30 days. January has 31 days, so 30 elapsed days after the first is 31 January 2024.
Assumptions and limits
- The start is day zero, not day one of an inclusive count.
- The offset counts calendar days, not working days.
- Date-only arithmetic ignores daylight-saving hours; valid input and output years are 0001–9999.
Questions people ask
How do I subtract days?
Enter a negative day offset. The sign supplies the direction; no separate operation switch is needed on this page.
Is adding 30 days the same as adding one month?
Not generally. Months have different lengths. Use Date Add/Subtract for a calendar-month offset and this page for an exact number of days.