How to add days to a date
✓ Verified in LibreOffice 25.8.7.3Shift a date forward or back by a number of days — due dates, deadlines, follow-ups.
The formula
| App | Formula | Notes |
|---|---|---|
| Excel | =A2+10 | Dates are numbers, so plain addition works. Use WORKDAY(A2,10) to skip weekends. |
| Google Sheets | =A2+10 | Identical. |
| LibreOffice Calc | =A2+10 | Identical. |
How it works
Spreadsheets store dates as day counts, so adding 10 literally moves the date 10 days: July 21 + 10 = July 31, with month and year rollover handled automatically. Subtraction goes back in time. For business days use WORKDAY (skips weekends, accepts a holiday list), and for whole months use EDATE — adding 30 days is not the same as adding a month.
Verified, not just documented
We ran =TEXT(DATE(2026,7,21)+10,"YYYY-MM-DD") in LibreOffice 25.8.7.3 (headless, with forced recalculation) and it returned 2026-07-31 — exactly the expected result. Every formula here is confirmed by actually executing it.