How to Find the Day of the Week

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It’s easy to find out the day of the week for births, weddings, and other historical events. Follow our instructions to calculate the day for any date in history—as far back as the mid-1700s.

For example, what day of the week was December 26, 2004, when the tsunami struck in the Indian ocean? Follow the example on the right as you read along:

  1. Take the last two digits of the year.
  2. Add to that one–quarter of those two digits (discard any remainder).
  3. Add to that the day of the month and the Month Key number for that month:

     

    January = 1 June = 5
    …leap year = 0 July = 0
    February = 4 August = 3
    …leap year = 3 September = 6
    March = 4 October = 1
    April = 0 November = 4
    May = 2 December = 6

     

  4. Divide the sum by 7. The remainder is the day of the week! One is Sunday, two is Monday, and so on.

Note: 

  • If you’re searching for a week prior to 1900, add 4.
  • The formula doesn’t work for days prior to 1753.
  • From 2000 to 2099, subtract 1 from the sum before dividing.

Here’s an Example:

The Dayton Flood was on March 25, 1913.

Last two digits of year 13
One-quarter of these two digits 3
Given day of month: 25
Key number for March 4

Sum: 45

45 divided by 7 = 6, with a remainder of 3. The flood took place on Tuesday, the third day of the week.

Monday’s child is fair of face,
Tuesday’s child is full of grace,
Wednesday’s child is full of woe,
Thursday’s child has far to go,
Friday’s child is loving and giving,
Saturday’s child works hard for a living,
And the child that is born on the Sabbath Day,
Is bonny and blithe and good and gay.

–an old English nursery rhyme

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