Date Calculator
The calculator adds days, business days, weeks, months and years to a date or takes them away, and shows the resulting date together with its weekday.
It is the everyday tool for deadlines: 45 days to reply, 14 business days for delivery, a three-month probation period, a one-year warranty.
Quick calendar-day presets
Result
March 1, 2026
Sunday · As YYYY-MM-DD: 2026-03-01
Month shifts clamp to the last day of the month: January 31 plus one month is February 28 or 29.
What the calculator can do
- Calendar days — a plain shift where weekends and holidays count like any other day.
- Business days — Saturdays and Sundays are skipped and only weekdays are counted.
- Weeks — seven days per week, so the weekday stays the same.
- Months and years — a calendar shift that clamps to the last day of the month.
How months are added
31 January plus one month is 28 February, or 29 February in a leap year. There is no 31 February, so the calendar clamps to the last day of the month instead of spilling into March.
Subtraction follows the same rule: 31 March minus one month lands on 28 or 29 February. If you need an exact 30-day shift, choose calendar days instead.
Common deadlines
| Deadline | Unit | From 15 January 2026 |
|---|---|---|
| 10 business days | business days | 29 January 2026 |
| 14 days | calendar days | 29 January 2026 |
| 30 days | calendar days | 14 February 2026 |
| 45 days | calendar days | 1 March 2026 |
| 3 months | months | 15 April 2026 |
| 1 year | years | 15 January 2027 |
What date will it be after adding days?
| Starting date | Add | Result |
|---|---|---|
| 29 July 2026 | 14 days | 12 August 2026 |
| 11 August 2026 | 45 days | 25 September 2026 |
| 29 June 2026 | 70 days | 7 September 2026 |
| 13 May 2026 | 182 days | 11 November 2026 |
| 6 October 2026 | 233 days | 27 May 2027 |
| 14 November 2026 | 266 days | 7 August 2027 |
Watch out when counting deadlines
- Check where the count starts: on the day of the event or the day after it.
- Business days here ignore public holidays — check the working calendar for your country.
- When a deadline lands on a weekend, many rules move it to the next working day.
- For long periods, counting in months and years is safer than converting them to days.
Frequently asked questions
How do I add days to a date?
Enter the starting date, choose "add", then type the amount and pick a unit. The calculator returns the date and its weekday.
How do I find the date N business days from now?
Choose the business days unit — Saturdays and Sundays are skipped and only weekdays are counted.
Why is 31 January plus one month 28 February?
Because 31 February does not exist. A calendar shift clamps the day to the end of the month rather than rolling into March.
Are public holidays taken into account?
No. Only Saturdays and Sundays are skipped, because holidays depend on the country and the year.
Can I subtract days from a date?
Yes — choose "subtract" and the calculator moves the date backwards under the same rules.
What date will it be after adding N days?
Choose the starting date, calendar days, and the amount. For example, 45 days after 11 August 2026 is 25 September 2026.
Updated: 2026-08-09