How the date is worked out
Each part is applied in order on the calendar, including leap years and each month's real length.
result = start + years, then + months (clamped to month end), then + weeks × 7 + days
- Years are added first, then months. Each moves the calendar month and keeps the day of the month.
- If that day does not exist, such as 31 February, the last day of the month is used instead.
- Weeks are then added as 7 days each, followed by the days.
- With business days on, the days amount skips Saturdays and Sundays. Years, months and weeks still move by the calendar.
- Subtracting works the same way, backwards.
Worked example — Fri 23 Oct 2026 + 30 days = Sun 22 Nov 2026. Adding 1 month to Sat 31 Jan 2026 gives Sat 28 Feb 2026, because February has no 31st.
Date examples
| Start date | Operation | Months | Days | Result date |
|---|---|---|---|---|
| 23 Oct 2026 | Add | 0 | 30 | Sun 22 Nov 2026 |
| 23 Oct 2026 | Add | 0 | 90 | Thu 21 Jan 2027 |
| 31 Jan 2026 | Add | 1 | 0 | Sat 28 Feb 2026 |
| 31 Jan 2024 | Add | 1 | 0 | Thu 29 Feb 2024 |
| 1 Mar 2026 | Subtract | 0 | 1 | Sat 28 Feb 2026 |
Swipe the table sideways to see the rest.
Calendar days unless shown otherwise.
Things to consider
- For a 90 day deadline, check whether the rules count calendar days or business days.
- Use months, not 30 days, for monthly bills: 1 month from 15 Mar is 15 Apr.
- Business days skip weekends only. Check public holidays in your state or territory separately.
- Tap a quick chip to see 7, 30 or 90 days from your start date at a glance.
Frequently asked questions
What date is 30, 60 or 90 days from today?
Leave the start date on today and tap +30, +60 or +90 days. Each chip shows its date straight away.
How are months added?
The month moves and the day stays the same. If that day does not exist, the last day of the month is used, so 31 January plus 1 month is 28 February, or 29 February in a leap year.
What is the difference between business days and calendar days?
Calendar days count every day. Business days count only Monday to Friday, so Friday plus 1 business day is the next Monday. Public holidays are not excluded.
Does it count the start date?
No. Adding 1 day to Monday gives Tuesday. To count the days between two dates, with an option to include the end date, use the Days Calculator: Days Between Two Dates.
Are leap years handled?
Yes. 31 January 2024 plus 1 month is 29 February 2024, and 29 February 2024 plus 1 year is 28 February 2025.
Can I go back in time?
Yes. Choose Subtract. 1 March 2026 minus 1 day is 28 February 2026.
Results are estimates for general information only, not financial, medical or professional advice.