Date Calculator
Add or subtract days from a date to find the resulting date and weekday.
Date Calculator
Select a date and number of days.
What This Calculator Does
Adding days to a date is not as simple as adding to the day number - you have to roll over the end of each month, and February even changes length in leap years. This tool handles all of that: pick a start date, add or subtract any number of days, and it gives the exact resulting date and the day of the week it lands on.
How to Use It
- Choose add days or subtract days.
- Pick the start date and enter the number of days.
- Read the resulting date and weekday.
Worked Examples
| Start date | Operation | Result |
|---|---|---|
| 2026-01-01 | + 30 days | 2026-01-31 |
| 2026-01-01 | + 365 days | 2027-01-01 |
| 2026-03-15 | − 14 days | 2026-03-01 |
| 2026-12-31 | + 1 day | 2027-01-01 |
FAQ
How do you add days to a date?
Count forward from the start date, rolling over into the next month or year as needed. The tool also handles leap years automatically.
Can I count backward?
Yes. Choose “subtract days” to find a date in the past.
How is this different from the days-between calculator?
This one moves a known number of days from a date; the days between dates calculator counts the days between two known dates.