Date Calculator

Calculate the number of days between two dates, or add and subtract years, months, weeks, and days from a date. Supports business days calculation.

Days Between DatesAdd / SubtractBusiness DaysYears & MonthsWeeks & Days
Two calculation modes:
Days Between Dates — find the exact difference between two dates.
Add / Subtract — calculate a future or past date from a starting point.

Days Between Two Dates

Find the number of years, months, weeks, and days between dates

About the Date Calculator

The Date Calculator offers two core functions: finding the difference between two dates, and computing a new date by adding or subtracting a time interval.

The Days Between Dates mode calculates the exact span in years, months, weeks, days, and business days. The optional "Include end day" checkbox adds one day to the total (useful when counting both the start and end date as full days).

The Add / Subtract mode lets you find a future or past date by specifying years, months, weeks, and days to add or subtract. The "Business days" option skips weekends when counting.

All calculations are based on the Gregorian calendar, the most widely used calendar system worldwide.

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Quick Reference

  • • 1 year = 365 days (366 in leap year)
  • • 1 month = 28–31 days
  • • 1 week = 7 days
  • • Business days exclude weekends
  • • Gregorian calendar used worldwide
  • • Leap years: divisible by 4 (not 100, or by 400)

2026 U.S. Federal Holidays

  • New Year's DayJan. 1
  • MLK Jr. DayJan. 19
  • Presidents' DayFeb. 16
  • Memorial DayMay 25
  • JuneteenthJun. 19
  • Independence DayJul. 4
  • Labor DaySep. 7
  • Columbus DayOct. 12
  • Veterans DayNov. 11
  • ThanksgivingNov. 26
  • ChristmasDec. 25

Frequently Asked Questions

January (31), February (28 or 29 in leap years), March (31), April (30), May (31), June (30), July (31), August (31), September (30), October (31), November (30), December (31). A helpful mnemonic: knuckle months have 31 days, valley months have 30 (or 28/29 for February).