Date Calculator
Add or subtract days from any date, or find exactly how many days fall between two dates.
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This tool does date arithmetic so you do not have to. Add or subtract any number of days from a date, with an option to skip weekends, or count the total days between two dates.
Deadline in 45 working days? Project starting 90 calendar days from today? Contract running for 6 months? This covers it.
How we work it out
Calendar day mode adds or subtracts the exact number of days from the start date, including weekends. Working day mode counts forward or backward, skipping Saturday and Sunday. The days-between mode gives the calendar days between the two dates, plus the working days from the start date to the end date counting both of them, and the full weeks.
How it's worked out
- Adding or subtracting days moves along the real calendar, so months of different lengths and leap years are handled for you.
- With skip weekends switched on, Saturdays and Sundays are not counted as days.
- Between two dates, it counts the days from one to the other. It also shows the whole weeks and leftover days, and how many of those days fall from Monday to Friday.
30 days after 15 January is 14 February, because January has 31 days. From 1 March to 1 April is 31 days, which is 4 weeks and 3 days.
Days in each month
| Month | Days | First day of the month is day number |
|---|---|---|
| January | 31 | 1 |
| February | 28 (29 in a leap year) | 32 |
| March | 31 | 60 |
| April | 30 | 91 |
| May | 31 | 121 |
| June | 30 | 152 |
| July | 31 | 182 |
| August | 31 | 213 |
| September | 30 | 244 |
| October | 31 | 274 |
| November | 30 | 305 |
| December | 31 | 335 |
Counting from 1 January as day 1, in a year that is not a leap year. A leap year is every fourth year, except century years that are not divisible by 400, so 2000 and 2028 are leap years and 2100 is not.
Common mistakes
- Counting the first and last day both when working out a deadline, giving a day too many.
- Treating 30 days as a month. Months have different lengths.
- Forgetting leap years when going across several years.
Questions
Does it include bank holidays?
No. Working day mode skips weekends only. Bank holidays vary by country and region, so you would need to subtract those manually.
Does the start date count as day one?
No. The count starts the day after the start date. So adding 1 day to Monday gives Tuesday, not Monday itself.
Does it deal with leap years?
Yes. It works with real calendar dates, so 29 February is counted when it falls in your range.
How do I find the number of days between two dates?
Pick the two dates and the tool counts them for you. Check the start date setting if you want the first day counted.
Deadline not for a while yet.