Why 5 Fridays, 5 Saturdays and 5 Sundays don’t occur every 823 years
More About Special Dates
The Truth is…
The first three weekdays of any 31-day month are repeated 5 times within that month. So, any month that has 31 days and begins on a Friday has 5 Fridays, 5 Saturdays, and 5 Sundays. And this happens much more often than every 823 years.
Have a look at our calendars and take it to the test!
Proof in cold print: July 2011 and July 2834 are not even the same.
Repeating Calendars
The next time that the 2011 calendar repeats itself is in the year 2022, which is only 11 years later. What’s more, a calendar month that contains 5 Fridays, 5 Saturdays and 5 Sundays occurs nearly every year: Both July 2011 and March 2013 have 5 Fridays, Saturdays and Sundays. The next July with same days as July 2011 is July 2016.
It does not repeat after 823 years at all
Even the claim that the year 2834 has the same calendar as the year 2011 is false (see picture).
For instance, July 2011 has 5 Fridays, Saturdays and Sundays. 823 years later, July 2834 has 5 Saturdays, Sundays and Mondays. That is a 5th Monday instead of a 5th Friday.
Variations of the urban myth:
- This year July has 5 Fridays 5 Saturdays and 5 Sundays. This happens once every 823 years. This is called money bags.
- This year, July has 5 Fridays, 5 Saturdays and 5 Sundays. This happens only once every 823 years.
- This year October will have 5 Sundays, 5 Mondays and 5 Saturdays. This happens only every 823 years.
- 2010: October will have 5 Sundays, 5 Mondays & 5 Saturdays which only happens every 823 years
- October 2010 has 5 Fridays, 5 Saturdays and 5 Sundays. Only happens every 823 years…
How recurring calendar months work
Every year has 7 months with 31 days. Each of these 7 months has three weekdays of which there are 5. There are 7 different days a month can start on. So on average, over time, each combination happens once yearly. But for each individual year, there are only 6 of 7 combinations, and two 31-day months start on the same weekday.
In a common/regular year, January and October look the same. In a leap year, January and July look the same.
5 of the same day in one month in 2011
| Days that occur 5 times, on these dates: | ||||
|---|---|---|---|---|
| 1 / 8 / 15 / 22 | 2 / 9 / 16 / 23 | 3 / 10 / 17 / 24 | ||
| 31 day month | 29th of month | 30th of month | 31st of month | Comments |
| January 2011 | 5 Saturdays | 5 Sundays | 5 Mondays | Same as October |
| March 2011 | 5 Tuesdays | 5 Wednesdays | 5 Thursdays | |
| May 2011 | 5 Sundays | 5 Mondays | 5 Tuesdays | |
| July 2011 | 5 Fridays | 5 Saturdays | 5 Sundays | |
| August 2011 | 5 Mondays | 5 Tuesdays | 5 Wednesdays | |
| October 2011 | 5 Saturdays | 5 Sundays | 5 Mondays | Same as January |
| December 2011 | 5 Thursdays | 5 Fridays | 5 Saturdays | |
5 of the same day in one month in 2012
| Days that occur 5 times, on these dates: | ||||
|---|---|---|---|---|
| 1 / 8 / 15 / 22 | 2 / 9 / 16 / 23 | 3 / 10 / 17 / 24 | ||
| 31 day month | 29th of month | 30th of month | 31st of month | Comments |
| January 2012 | 5 Sundays | 5 Mondays | 5 Tuesdays | Same as July |
| March 2012 | 5 Thursdays | 5 Fridays | 5 Saturdays | |
| May 2012 | 5 Tuesdays | 5 Wednesdays | 5 Thursdays | |
| July 2012 | 5 Sundays | 5 Mondays | 5 Tuesdays | Same as January |
| August 2012 | 5 Wednesdays | 5 Thursdays | 5 Fridays | |
| October 2012 | 5 Mondays | 5 Tuesdays | 5 Wednesdays | |
| December 2012 | 5 Saturdays | 5 Sundays | 5 Mondays | |
Other calendars
- Repeating Calendars – Which years share the same calendar?
- Calendar Generator – Create a calendar for any year
- Calendar for 2013
Date Calculators
- Duration between two dates – Calculates number of days
- Date Calculator – Add or subtract days, months, years
- Birthday Calculator – Find when you are 1 billion seconds old
- Weekday Calculator – What Day is this Date? – Find the weekday for any date.
Related links
- Countdown to New Year
- Moon Phase Calculator – Calculate moon phases for any year
- Seasons Calculator