Add or subtract calendar days from any date, see the resulting weekday, and compare common day offsets such as 7, 14, 30, 60 and 90 days.
Calendar-day differences, business-day counting, days-until questions and date arithmetic.
Choose a starting date, select Add or Subtract, and enter the number of calendar days. The result shows the exact date and weekday. Turn on Count the starting date when your rule treats the starting date as day 1.
Use the quick buttons above the results for 7, 14, 30, 60, 90, 180 or 365 days. These are calendar days, so Saturdays, Sundays and holidays are included.
| Offset | Common use |
|---|---|
| 7 or 14 days | Short follow-up dates and two-week periods |
| 30 or 60 days | Deadlines, notices and future-date planning |
| 90 days | Quarter-length calendar offsets |
| 365 days | One-year calendar-date checks |
If September 16, 2026 is the starting date and you add 30 days without counting the starting date, the result is October 16, 2026. If a deadline specifically counts the starting date as day 1, use the inclusive option.
This tool uses calendar days. For weekdays only, use the business days calculator. To compare two existing dates, use the days between dates calculator or weeks between dates calculator.
For a countdown, try the days until a date calculator. For a step-by-step explanation, see how to add days to a date.
Start on January 1, 2026 and add 30 days. Standard date arithmetic gives January 31, 2026 because January 1 is day zero. If you choose to count the starting date as day one, day 30 is January 30, 2026.
What this does not do: ordinary day offsets include Saturdays, Sundays, and public holidays. If you need only Monday–Friday dates, use the Business Days Calculator. Always confirm deadline rules separately where a contract, court, or agency uses its own counting convention.
Yes. It adds or subtracts calendar days, including weekends.
Yes. Choose Subtract instead of entering a negative number.
When enabled, the starting date is treated as day 1, so a 30-day inclusive count ends one calendar day earlier than a standard 30-day offset.
Use the calculator above for any offset. These common calendar-day intervals are especially useful for deadlines, follow-ups, return windows, project schedules and planning.
| Offset | Use it for | Related example |
|---|---|---|
| 7 days | One-week follow-up | Add 7 calendar days |
| 14 days | Two-week deadline | Add 14 calendar days |
| 30 days | Monthly-style deadline | |
| 60 days | Longer review window | |
| 90 days | Quarter-length planning window |
Enter a positive number of days to move forward from the starting date or choose subtraction to move backward. The result shows the calendar date and weekday so you can verify the target day at a glance.
This calculator counts every calendar day, including Saturdays and Sundays. If you need weekdays only, use the Business Days Calculator. For differences between two known dates, use the Days Between Dates Calculator.
See the Dates & Deadlines topic hub for date arithmetic, days-until questions, business-day counting and more worked examples.
See how formulas, sources and limitations are handled across ERICH Calculators.