Day of the Week Calculator

Use the calculator below to find the day of the week of any date. It also gives out a few facts as well as the calendar of the month.


RelatedDate Calculator | Age Calculator

ISO 8601

The International Organization for Standardization (ISO) is the regulator of ISO 8601, which is the international standard for covering the exchange of data related to date or time. Though it is used by the majority of the world, especially developed, not all adhere by this standard. The internationally recognized method of conveying the day of the week is governed by ISO 8601, which uses an algorithm for calculating the day of a week in a particular month and year. It is called Zeller's congruence, which was invented by Christian Zeller. Monday is the official first day of the week according to ISO 8601.

Gregorian Calendar

The Gregorian Calendar, named after Pope Gregory XIII, is based on the time it takes the moon to make one full revolution around the earth (roughly one month) and the Sun to make a full revolution around the Earth (roughly one year). Because celestial bodies of such close proximity can be widely encountered, it was common in ancient times to use them to tell time and/or date. This method was further refined into what we now know as the current Gregorian Calendar.

Where do Their Names Come From?

The names of the days of the week are mostly derived from the names of Roman gods (which current names of celestial bodies are also derived from) from the Hellenistic, which is the period in history between the death of Alexander the Great in 323 BC and the rise of the Roman Empire in 31 BC. For instance, in the Roman calendar, Sunday is named after Sol, a Roman Sun god, and Saturday after Saturnus, the Roman god of wealth and liberation, amongst many other things. The others are a bit more obscure; Monday was named after Luna, the divine embodiment of the moon, Tuesday after Mars, Wednesday after Mercurius (Mercury), Thursday after Jove (Jupiter), and Friday after (Venus). From these origins, Latin names for the days of the week permeated into other cultures and languages such as French and German. It even seeped into cultures all around the world, such as Japanese and India. For instance, the word Friday in Japanese is formed from the word "kinsei", which means Venus, and "yobi", which means day. The Japanese word for Tuesday, which is "ka youbi", literally translates to "fire day", in relation to Mars. Also, the word for Thursday in most languages spoken in India is "Guruvara", where "guru" is the style of Brhaspati, the guru to the gods and regent of the planet Jupiter.

Trivia About Each Day