Formula
The new date is the start plus the day count, using calendar days:
New date = start date + days
The subtract page removes days. The date difference page counts the gap instead of moving a date.
Assumptions
- Days are whole calendar days.
- The count can be zero.
Worked example
January 1, 2026 plus 30 days is 2026-01-31.
Input definitions
- Days to add
- A whole number from 0 to 3,660.
Limitations
Time of day and time zones are not included.
Questions
Does this skip weekends?
No. Every calendar day counts. Working days are a separate page.
Can I subtract?
Use the date subtract calculator.