Date Calculator
This free date calculator computes the difference between two dates. It can also add to or subtract from a date.
Days Between Two Dates
Find the number of years, months, weeks, and days between two dates.
Add or Subtract from a Date
About this Tool
History of the Gregorian Calendar
The Gregorian calendar is the most prevalently used calendar today. Within this calendar, a standard year consists of 365 days with a leap day being introduced to the month of February during a leap year. The months of April, June, September, and November have 30 days, while the rest have 31 days except for February, which has 28 days in a standard year, and 29 in a leap year.
The Gregorian calendar is a reformed version of the Julian calendar, which was itself a modification of the ancient Roman calendar. In 46 BC, the calendar was further reformed by Julius Caesar. He inserted an additional 10 days into the Republican calendar, making the total number of days in a year 365, and added the intercalation of a leap day every fourth year.
Despite all efforts, the Julian calendar still required further reform, since the calendar drifted with respect to the equinoxes and solstices by approximately 11 minutes per year. By 1582, this resulted in a difference of 10 days from what was expected. Pope Gregory XIII addressed this by making the day after October 4, 1582, October 15. An adjustment was also made so that century years not divisible by 400 would not be leap years. These changes reduced the error from 1 day in 128 years, to 1 day in 3,030 years.
Holidays
A holiday is a day that, either by custom or by law, is set aside such that regular activities like going to work or school are suspended, or at least reduced. This calculator is mainly geared towards U.S. holidays, but holidays specific to a given country can be entered manually. Certain holidays such as New Year's Day are referred to as "fixed holidays," since they fall on the same date every year. Others, such as the birthday of Martin Luther King, Jr., occur on a "floating Monday" (the third Monday of January).
2025 U.S. Federal Holidays
| New Year's Day | Jan. 1, 2025 |
| Martin Luther King Jr. Day | Jan. 20, 2025 |
| President's Day | Feb. 17, 2025 |
| Memorial Day | May. 26, 2025 |
| Juneteenth Day | Jun. 19, 2025 |
| Independence Day | Jul. 4, 2025 |
| Labor Day | Sep. 1, 2025 |
| Columbus Day | Oct. 13, 2025 |
| Veteran's Day | Nov. 11, 2025 |
| Thanksgiving | Nov. 27, 2025 |
| Christmas | Dec. 25, 2025 |