Quantcast
How to Find the Day of the Week for Any Date | The Old Farmer's Almanac

Order Your Almanac Today!

How to Find the Day of the Week for Any Date

Calculate What Day of the Week it is With Our Simple Formula

Catherine Boeckmann
Print Friendly and PDF
No content available.

What day did that happen? It’s easy to find the day of the week for births, weddings, deaths, and other historical events. Follow our simple instructions to calculate the day for any historical or future date—as far back as the mid-1700s.

For example, what day of the week was December 26, 2004, when the tsunami struck the Indian Ocean? Follow the example 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:

    Read Next

    January = 1June = 5
    …leap year = 0July = 0
    February = 4August = 3
    …leap year = 3September = 6
    March = 4October = 1
    April = 0November = 4
    May = 2December = 6
  4. Divide the sum by 7. The remainder is the day of the week! One is Sunday, two is Monday, and so on. If there is no remainder, the day is Saturday.

Note: 

  • If you’re searching for a week before 1900, add 2 to the sum before dividing; before 1800, add 4.
  • The formula doesn’t work for days before 1753.
  • From 2000 to 2099, subtract 1 from the sum before dividing.

Here’s an Example:

A tsunami occurred in the Indian Ocean on December 26, 2004.

 
Last two digits of year04
One-quarter of these two digits1
Given day of month:26
Key number for December6

Sum: 37

Because 2004 is in the range of 2000 to 2099, subtract 1 from 37. This yields 36.

36 divided by 7 = 5, with a remainder of 1. The tsunami took place on Sunday, the first 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

Calendar
About The Author

Catherine Boeckmann

Catherine Boeckmann loves nature, stargazing, and gardening so it’s not surprising that she and The Old Farmer’s Almanac found each other. She leads digital content for the Almanac website, and is also a certified master gardener in the state of Indiana. Read More from Catherine Boeckmann

2023 Gardening Club

More Like This

Comments

Tino (not verified)

2 weeks 3 days ago

Can you explain the month Key number.
In your example Dec = 6, and in a comment Feb = 4
How are these calculated?
Thanks

You have to trust that Jan = 1. For the next months, keeping adding the extra days past 28 (which when divided by 7 =0). So, 1 + 3 (for Jan.) = 4 for Feb. Then 4 + 0 (for Feb) = 4 for March... then 4 + 3 (for March) = 7 for April but 7 is 0 because there are 7 days in a week. Then 0 + 2 (for April) = 2 for May and so on.

Kishan (not verified)

3 months 2 weeks ago

And what id the one-quater is a decimal can you say an example with that?

Hi, there,

Let’s try February 27, 1975.

1) Last two digits of the year are: 75

2) Add one-quarter of those two digits: 75/4 = 18.75.  We would discard anything past the decimal point, so just “18”

3) Add day of the month: 27

4) Add Month Key number for February: 4

5) Sum so far: 75 + 18 + 27 + 4 = 124

6) Because the year is between 1900 and 1999, we do not need to add or subtract anything before dividing.

7) Divide the sum by 7: 

For this division, we use the long division method to find the remainder. (Please forgive the rough formatting for long division.)

124/7 = 

    _17
7 | 124
      7
    —
      54
      49
      –
        5

5 is the remainder. This corresponds to Thursday.

Hope this helps!

This did not work in the case of June 18th, 1997

97/4 = 24.25
24 + 97 = 121
121+ 18 = 139
139+ 5 = 144
Since it’s not between 2000-2099 I didn’t subtract.
144/7
20.5
5 = Thursday

June 18th 97 was a Wednesday. Any reason this was wrong?

Hi, Vince,

For this formula to work, we need to use long division rather than a calculator or similar to determine the remainder. A calculator would say 20.571… is the result of 144 divided by 7, but the “0.5” would not be the remainder. So, in the below long division formula, “4” would be the remainder — which is Wednesday.

   _ 20
7 | 144
     14 
    —
      04


Hope this helps!     

 

 

Hi, Tom,

Using the long division method, 7 goes into 12 (first two digits of “124”) one time. (The number “1” goes up top, over the 2 in “124.”) Put “7” under the “12,” and subtract. So 12 minus 7 is 5. Then, bring down the “4” in the “124” (the next digit to right) to make “54.” Then, 7 goes into “54” seven times. (The number “7” goes up top, over the “4” in 124.) So 7 times 7 is 49. Subtract 49 from 54, and we get 5, the remainder. Hope this helps!

   _17
7 | 124
      7
    —
      54
      49
      —
        5

Kishan (not verified)

3 months 2 weeks ago

what is the number to be subtracted for other centuries, as you stated for the 21st century it is one but for others?