Date period calculator

Date Calculator

Days Between Two Dates

Find the number of years, months, weeks, and days between dates. Click "Settings" to define holidays.

Add to or Subtract from a Date

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. The ancient Roman calendar was believed to be an observational lunar calendar, based on the cycles of the moon's phases. The Romans were then believed to have adopted a 10-month calendar with 304 days, leaving the remaining 50 or so days as an unorganized winter. This calendar allowed the summer and winter months to become completely misplaced, leading to the adoption of more accurate calendars.

The Republican calendar later used by Rome followed Greek calendars in its assumptions of 29.5 days in a lunar cycle and 12.5 synodic months in a solar year, which align every fourth year upon the addition of the intercalary months of January and February. From this point, many attempts were made to align the Republican calendar with the solar year including the addition of an extra month to certain years to supplant the lack of days in a particular year. In 46 BC, the calendar was further reformed by Julius Caesar, introducing an algorithm that removed the dependence of calendars from the observation of the new moon. In order to accomplish this, Caesar inserted an additional 10 days into the Republican calendar, making the total number of days in a year 365. He also added the intercalation of a leap day every fourth year, all in an attempt to further synchronize the Roman calendar with the solar 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 essentially skipping 10 days in the date, making the day after October 4, 1582, October 15. An adjustment was also made to the algorithm of the Julian calendar that changed which century years would be considered leap years. Under the Gregorian calendar, 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 with respect to the current value of the mean solar year.

The adoption of the Gregorian calendar occurred slowly over a period of centuries, and despite many proposals to further reform the calendar, the Gregorian Calendar still prevails as the most commonly used dating system worldwide.

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. The term "holiday" can be interpreted differently, depending on the region. In the U.S., paid leave is typically referred to as "vacation," while national, religious, or cultural days off are referred to exclusively as "holiday." In some regions, however, such as the United Kingdom or former British colonies, the term holiday can also refer to paid leave.

Generally, holidays are meant to commemorate some event, person, or group of cultural or religious significance. Although certain holidays, such as Christmas and New Year's Day, are widely celebrated worldwide, most countries have their own set of holidays that are specific to the country, and even the same holidays may be observed differently within countries: some may receive a full suspension of typical daily activities, while others may only get partial days off. Certain countries have holidays that essentially shut down almost all businesses. As an example, in Brazil, Carnaval do Brasil results in almost a full week in which only industrial production, retail establishments, or carnival-related businesses, function.

This calculator is mainly geared towards U.S. holidays, but holidays specific to a given country can be entered manually. Certain holidays can also be excluded. For a further level of specificity, federal holidays in the U.S. refer to holidays that have been recognized by the U.S. government; on these days, non-essential federal government offices are closed, and all federal employees receive paid leave. This is not necessarily true in the private sector, however, and which federal holidays a private sector employee receives is largely dependent on the discretion of the company. In some cases, an employee who is required to work on a federal holiday may receive compensation in the form of holiday pay in addition to their regular wages.

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., don't have a fixed date, because they occur on a "floating Monday"; in this particular case, the holiday occurs on the third Monday of January. Another widely observed holiday in the U.S., Thanksgiving, occurs on a "floating Thursday," the fourth Thursday In November, hence the dates of these holidays vary by year. Below are two tables showing the dates of federal holidays in the U.S. for 2023 and 2024.

2023 U.S. Federal Holidays

2024 U.S. Federal Holidays

Period Calculator

Use this calculator to estimate the future period days or the most probable ovulation days.

Menstrual cycle

The menstrual cycle is a series of changes that occur in a woman's body as part of the preparation for the possibility of pregnancy occurring. It is a cycle that usually begins between 12 and 15 years of age that continues up until menopause, which, on average, occurs at the age of 52. The menstrual cycle is typically counted from the first day of one period to the first day of the next. It is controlled by the rise and fall of hormones. The length of a woman's menstrual cycle varies. A regular menstrual cycle is considered to be a menstrual cycle where the longest and shortest cycles vary by less than 8 days. The average menstrual cycle lasts 28 days.

As part of the menstrual cycle, the lining of the uterus thickens, and an egg, which is required for pregnancy to occur, is produced. The egg is released from the ovaries in a process called ovulation, which corresponds with the time during which a woman is most fertile (~5 days before ovulation, up through 1-2 days after ovulation). If the egg is not fertilized, pregnancy cannot happen, and the lining of the uterus will shed during a menstrual period, after which the cycle restarts.

A period, a commonly used term for referring to menstruation, is a woman's regular discharge of blood and mucosal tissue that occurs as part of the menstrual cycle. Bleeding and discharge of the mucosal lining of the uterus, through the vagina, usually lasts between 2 and 7 days. It occurs in the early phases of the menstrual cycle, referred to as the menstrual phase, which begins when the egg from a previous cycle is not fertilized. Periods stop during pregnancy, and typically do not resume during the early stages of breastfeeding. Periods also eventually stop permanently during menopause, usually between the ages of 49 and 52, and can be defined as having no vaginal bleeding for a year.

The Period Calculator estimates period days and the most probable ovulation days in calendar form. Period days are the days during which bleeding and discharge occur. The most probable ovulation days are the days during which a woman is most likely to ovulate.

Calculator of days in the period (calendar, working) \ ConsultantPlus

Interval between dates

End date

add subtract

calendar days working days weeks

Include start date

Calculation possible from 01. 01.1992

Calculation of values ​​before 01/01/1992 is not performed

End date, taking into account non-working days established by Decrees of the President of the Russian Federation*

Note

The calculator does not take into account additional non-working (holiday) days of the constituent entities of the Russian Federation and non-working days that may be introduced in the constituent entities of the Russian Federation in connection with the spread of coronavirus (for example, Decree of the Mayor of Moscow dated 12. 06.2021 No. 29-MIND).

Days March 30 to April 30, 2020, May 6 to May 8, 2020, June 24, 2020, July 01, 2020, May 4 to May 7, 2021, October 30 to November 7, 2021 were declared non-working by Decrees of the President of the Russian Federation dated 03/25/2020 No. 206, from 04/02/2020 No. 239, from April 28, 2020 No. 294, from 29.05.2020 No. 345, from 06/01/2020 No. 354, from 04/23/2021 No. 242, from 20.10.2021 No. 595.

DAYS (function DAYS) - Microsoft Support

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This article describes the formula syntax and usage of the DAYS function in Microsoft Excel. To learn more about the DAY function, see the DAY function article.

Description

Returns the number of days between two dates.

Syntax

DAYS(end_date, start_date)

The DAYS function has the following arguments.

• end_date Required argument. Start_date and end_date are two dates, the number of days between which you want to calculate.

• Start_date Necessarily. Start_date and end_date are two dates, the number of days between which you want to calculate.

Note: Dates are stored in Excel as sequential numbers so that they can be used in calculations. By default, January 1, 1900 is 1, and January 1, 2008 is 39448 because January 1, 1900 is 39447 days.

Remarks

• If both arguments are numeric, the DAYS function subtracts the start date from the end date to get the number of days between them.

• If one of the arguments is text, it is treated as DATEVALUE(date_as_text) and returns an integer date instead of a time component.

• If the date arguments are numeric values ​​that are not in the range of a valid date, the DAYS argument returns #NUM! #VALUE! error value.

• If the date arguments are strings that cannot be used as valid dates, then #VALUE! #VALUE! error value.

Example

Copy the sample data from the following table and paste it into cell A1 of a new Excel sheet. To display formula results, select them and press F2 followed by ENTER. Change the width of the columns, if necessary, to see all the data.