Date Calculator

Count the days between two dates, including business days, or add and subtract days, weeks, months or years to find a new date.

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Days between
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Weeks and days–
Years, months, days–
Business days–
Hours–

Counting days between two dates

Pick a start and end date to see the number of days between them, plus the same span in weeks, in years-months-days, in hours and in business days. For example, from January 1 to December 31, 2026 is 364 days, or 365 if you include the end date.

Adding or subtracting time

Switch to Add or subtract to find a date a certain amount of time away. 90 days after October 24, 2026 is January 22, 2027. Choose business days to skip weekends, which is useful for delivery estimates, notice periods and deadlines counted in working days.

Everyday uses

  • Deadlines: 30, 60 or 90 days from an invoice or notice date.
  • Countdowns: days until a wedding, vacation or due date.
  • Projects: working days between kickoff and launch.
  • Travel: length of a trip, including both the first and last day.

Things to keep in mind

  • Public holidays are not excluded from business days, so subtract any that apply.
  • Adding months keeps the same day of the month when possible. If that day does not exist, the last day of the month is used.
  • Leap years are handled automatically.

Want someone's exact age? Use the age calculator.

Last reviewed October 2026.

Frequently asked questions

Does the day count include the start and end dates?

By default the calculator counts the days from the start date up to the end date, the same way you would say there is 1 day between today and tomorrow. Tick "Include the end date" to count both days, which is how many people count the length of a trip or event.

How are business days counted?

Business days are Monday through Friday. Weekends are left out. Public holidays are not removed automatically, because they differ by country, state and employer, so subtract any holidays that apply to you.

What happens when I add a month to January 31?

Months have different lengths, so the result moves to the last day of the shorter month. January 31 plus one month is February 28, or February 29 in a leap year.

How many days are in a year?

A common year has 365 days and a leap year has 366. Leap years happen every 4 years, except years divisible by 100 that are not divisible by 400. So 2000 was a leap year, but 1900 was not.

Can I count backward from a date?

Yes. In the add or subtract mode, choose "Subtract" to find a date in the past, such as 90 days before a deadline.