Date Calculator
Last updated: October 15, 2026
Add or subtract a number of days from a calendar date and show the resulting date.
Resulting date
—
- Starting date: —
- Applied day offset: —
- Day of week: —
On this page
Quick summary: Add or subtract a number of days from a calendar date and show the resulting date.
Read the complete guide
Updated reference sections in this guide are in English.
What this calculator estimates
Add or subtract a number of days from a calendar date and show the resulting date.
How to use it
Enter Starting year; Starting month (1–12); Starting day; Days to add or subtract. Select Calculate to update the results.
How the calculation works
The entered calendar date is converted to UTC and the selected number of 24-hour days is added or subtracted.
Worked example: starting scenario
| Starting year | 2026 |
|---|---|
| Starting month (1–12) | 7 |
| Starting day | 24 |
| Days to add or subtract | 100 |
| Resulting date | 2026-11-01 |
|---|---|
| Starting date | 2026-07-24 |
| Applied day offset | +100 days |
| Day of week | Sunday |
Important limitations
The result treats each offset as a calendar day and does not model business days, holidays or local daylight-saving transitions.