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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
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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: At this step, it may be easiest to use long division to get the remainder. When using a calculator, after you divide the sum by 7, you’ll need to multiply the numbers after the decimal (not the whole number) in the result by 7 and then round to the nearest whole number to get the remainder.]

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

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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
 

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Comments

kristopher (not verified)

1 week 5 days ago

hi can u solve jan 8 1984, i solved it multiple times but the answer is 1.9 so on so it would be 2 which is monday but it's sunday please help haha

Hi Kristopher,

I’m just guessing, but I think the fact that 1984 was a leap year might be causing your miscalculation. As noted on the Month Key chart, Leap Year changes January’s 1 to a 0.

Which leads us to:

January 8, 1984

last two digits: 84

add one quarter of those digits: 84/4=21  84+21=105 

add day and month key: 105+0+8=113

divide sum by 7: 113/7=16 (remainder 1)

And the remainder of 1 tells us that January 8, 1984 was in fact a Sunday.

Hope that makes sense!

Wendy (not verified)

4 weeks ago

WRONG! You forgot to add the last two digits of the year before dividing by 7

Sarah (not verified)

5 months 1 week ago

Hi, we just found your website and are amazed. Just curious, how did you figure this formula out and what is this it called? Also how did you calculate the key numbers??
This is amazing thank you!

Riza (not verified)

5 months 3 weeks ago

How to find the one quarter of two Digits?

One quarter or two digits = the two digits (or any number of digits) divided by 4.
1/4 * 28 = 1/4 * 28/1 = (1 * 28) / (4 * 1) = 28/4 = 7

Ana (not verified)

7 months 3 weeks ago

this doesnt work for 3 of March 2147. Can anyone help?

Hi, Ana,

We’re not sure that the formula is intended for years beyond 2099. We’ve tried a few examples for years 2100 through 2199, and if one subtracts 3 instead of 1 before the last step, it works for the sample dates that we’ve tried, including March 3, 2147. But we’re not sure if it would apply to all dates in that yearly span.

Hope this helps!

 

Here's a method I've tested for all dates up to the year 5000. It generalizes the part of the method under the "Note" section. Instead of conditionally adding 2, 4, etc, always add a term. The term should be equal to (3 - y % 4) * 2 where y is the first two digests of the year.