Day of the week calculator

This day of the week calculator allows you to find the day of the week for any chosen date.

Upon changing a date, the calculator updates the displayed date details, including the day of the week and various statistics like the day’s position in the year, the number of days remaining, and the count of specific weekdays in the year.

Additionally, the calculator generates and showcases a calendar, highlighting the chosen date, while offering options to view the month’s days in a table format.

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What is a calendar?

Calendars serve as fundamental systems to organize time across civilizations, recording days, months, and years. They are shaped by the natural rhythms of celestial movements or cultural and religious practices. Among the various calendar systems, the widely adopted Gregorian calendar dominates global use. It’s structured with 12 months and either 365 or 366 days in a leap year.

The Gregorian calendar

The Gregorian calendar is the most widely used calendar system globally. It was introduced by Pope Gregory XIII in 1582 as a reform of the Julian calendar, which had accumulated discrepancies with the solar year.

Key features of the Gregorian calendar include:

1. Months: It consists of 12 months:
   • January
   • February
   • March
   • April
   • May
   • June
   • July
   • August
   • September
   • October
   • November
   • December
2. Leap years: To correct the Julian calendar’s overestimation of the length of a year, the Gregorian calendar introduced a rule for leap years. Years divisible by 4 are generally leap years, except for centennial years (divisible by 100) unless they are also divisible by 400. For example, 2000 was a leap year, but 1900 was not.
3. Adjustment of days: The Gregorian calendar adjusted the number of days in some months to better align with the solar year. February, for instance, has 28 days in common years and 29 days in leap years.
4. Standardization: It was widely adopted over time by different countries and replaced the Julian calendar due to its improved accuracy in approximating the solar year.
5. Accuracy: The Gregorian calendar is more accurate than the Julian calendar in terms of measuring the solar year, reducing the error in the length of the year to about 26 seconds.

The Gregorian calendar is used as the civil calendar in most countries today, though some cultures and religions use different calendar systems for religious or cultural purposes.

Weekday names

Weekday names, prevalent across languages, often trace their origins to ancient mythologies, celestial bodies, or deities.

The names of the weekdays in the Gregorian calendar have roots in ancient civilizations and mythology:

1. Monday: Derived from “Moon’s day,” honoring the Moon. In many languages, the name refers to the moon (e.g., lunes in Spanish, lundi in French).
2. Tuesday: Named after Tiw, the Norse god of war. The Latin name for Mars (Martis dies) is reflected in Romance languages (e.g., martes in Spanish, mardi in French).
3. Wednesday: Named after Odin or Woden, the chief Norse god. The Latin name for Mercury (Mercurii dies) is reflected in Romance languages (e.g., miércoles in Spanish, mercredi in French).
4. Thursday: Named after Thor, the Norse god of thunder. The Latin name for Jupiter (Jovis dies) is reflected in Romance languages (e.g., jueves in Spanish, jeudi in French).
5. Friday: Named after Frigg or Freyja, Norse goddesses. The Latin name for Venus (Veneris dies) is reflected in Romance languages (e.g., viernes in Spanish, vendredi in French).
6. Saturday: Named after Saturn, the Roman god of agriculture. Derived from the Latin name for Saturn (Saturni dies), which is reflected in Romance languages (e.g., sábado in Spanish, samedi in French).
7. Sunday: Named after the Sun, revered across many cultures. In Latin-based languages, it’s often named after the sun (e.g., Sunday in English, domingo in Spanish).

These names have historical, linguistic, and mythological connections, reflecting the influence of various ancient cultures on the calendar we use today.

ISO 8601

ISO 8601 stands as an international standard governing the representation of dates and times. It promotes a clear and unambiguous format for dates: YYYY-MM-DD (year-month-day). This standardized representation aids global communication and data exchange by minimizing ambiguity and ensuring consistency. Additionally, ISO 8601 defines a week date system (YYYY-Www-D), highlighting the week number and day within that week, offering a structured way to denote weeks in a year. Understanding diverse calendar systems and international standards like ISO 8601 fosters effective communication and accurate date representation across cultural and global contexts.