Date calculator

Days between two dates

Add or subtract days

Counting days: include the end date or not?

The calculator counts the days from the start date up to the end date, without counting the end date itself: from Monday to Friday of the same week is 4 days. If you need both days included, as when you count days of leave, add one. A period “of 30 days” starting on October 19 ends on November 17 if day 1 is October 19, and on November 18 if counting starts the next day; legal deadlines usually say which.

Weekdays and business days

Weekdays here are Monday to Friday. Business days also leave out holidays, which depend on your employer; the 11 US federal holidays are listed in work hours in a year. For shift workers, “days” in a contract or a rota usually means calendar days, since you work on weekends too.

Leap years and long periods

A leap year has 366 days, with February 29. The rule of the calendar we use is: years divisible by 4 are leap years, except years divisible by 100, which are leap years only if they are also divisible by 400. So 2028 is a leap year, 2100 will not be, and 2000 was. A period that includes February 29 is one day longer than the same dates in a normal year; from January 1 to December 31, 2027 is 364 days (365 counting both ends).

For week numbers, see how many weeks are in a year; for working days and hours, work hours in a year.

Dates on a shift rotation

Rotating schedules repeat every few days: 14 for a Pitman, 28 for a DuPont, 3 for a 24/48. To find whether you work on a given date, count the days from a day you know you started a block and divide by the cycle length; the remainder tells you where you are in the cycle. The shift calendar does this for every day of the year at once.

More guides

• Daylight saving time
• Weeks in a year
• UTC time
• EST time
• CST time
• PST to EST
• All guides

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