Not that I have friggatriskaidekaphobia or anything. But since today is Friday & 13th, lets put our Excel skills to test and find out when the next Friday the 13th is going to be.
(trivia: Check this for some interesting facts about Friday the 13th)
Finding Next Friday the 13th using Excel Formulas – Approach 1
Lets say, you have a date in cell C3, and you want to find out when the next Friday, the 13th is going to be starting the date in cell C3.
The first approach I can think of is pretty straight forward.
We list all the 13ths in a column and find the next 13th which is also a Friday. For this,
- In cell E3, we write =MONTH(C3)
- In cell F3, we write =YEAR(C3)
- We use these 2 cells to refer to the month and year of the starting date.
- Then, we write in an empty cell =DATE($F$3,$E$3+ROWS($A$1:A1),13) – lets say this cell is E5
- This gives us the 13th date of next month, from the start date in cell C3.
- Now, lets drag this formula and fill it down, for say, next 100 cells to get next 100 13ths.
- The ROWS($A$1:A1) portion generates continuous numbers from 1 thru 100 and thus we get next 100 13ths.
For more on this technique, read – Using ROWS() to generate a series of numbers
Once all the 13ths are listed, in an adjacent column, we can use WEEKDAY() formula to see if the 13th is a Friday – WEEKDAY(E5)=6
This column will have a bunch of TRUE & FALSE values.
Now to find the next Friday the 13th, we just look for TRUE value in this column (say F5:F104) use it to derive the date.
So this formula =DATE(F3,E3+MATCH(TRUE,$F$5:$F$104,0),13) should give us the next Friday, the 13th.
Break up of above formula:
- MATCH(TRUE,$F$5:$F$104,0) tells us the position of first TRUE value (ie first Friday, the 13th in our list)
- DATE(F3,E3+Match value, 13) gives the date of next Friday, the 13th
- Remember, F3 contains the year and E3 the month of starting date you entered in C3.
Finding Friday the 13th, 2nd Approach
While above approach works fine, it requires a few helper columns. So I got thinking, how can we write a one shot formula that gives us next Friday, the 13th date?
First the formula:
This is an array formula.
{ =DATE(YEAR($C$3), MATCH(TRUE, WEEKDAY(DATE(YEAR($C$3),MONTH($C$3)+ROW($A$1:$A$100), 13))=6,0) + MONTH($C$3),13) }
Scary formula indeed. We may have to coin a word for fear of long excel formulas – doubleXLformulaphophia.
How does this formula work?
Before understanding the portions of this formula, we need to understand the approach.
This formula uses similar thinking as of earlier formula. Just that it shrinks all those helper columns to an array and works the magic.
To find next Friday, the 13th, we need to list down next few 13ths and check which one is a Friday. Since Excel lookup formulas always return the first match, we find the first such Friday.
Parts of the formula:
- To get the next 100 13ths, we use, DATE(YEAR($C$3),MONTH($C$3)+ROW($A$1:$A$100), 13)
When used in an array formula, this gives us the 13th days of next 100 months.
(aside: technically, we do not need next 100 months. As per Wikipedia, the maximum gap between successive Friday, the 13ths is 14 months. more)
Also, note that we are using ROW() formula, not ROWS(), as we want all the row numbers for first 100 rows as an array.
- Once we have these 100 dates, we just check for their Fridayness with, WEEKDAY(100 dates))=6
This formula returns a 100 TRUE & FALSE values. TRUE, whenever the date is a Friday, FALSE, when it is not.
- Then, we find the first TRUE value (ie first occurrence of Friday, the 13th in next 100 months) with, MATCH(TRUE, next 100 dates’ Fridayness, 0)
This gives us the position of next TRUE value.
- Finally, we use that to construct the date of next Friday, the 13th – DATE(YEAR($C$3), MONTH($C$3) + first TRUE value, 13)
And that is how we find the next Friday the 13th based on the start date in cell C3.
Important Note:
Both approaches only search for Friday, the 13th starting next month of the date in C3. If C3 has a date prior to 13th and the 13th of that month is a Friday, the 13th, it would not be considered. For example, if you enter 10-JAN-2012 in C3, both formulas would find next Friday the 13th as April 13, 2012 not Jan 13, 2012.
Download Friday, the 13th Example Workbook
I have made a colorful (and almost gory) download workbook. Even if you do not want to learn this, I suggest downloading the file, for fun!
Click here to download the Friday, 13th calculations workbook & play with it.
Bonus: It has homework too!
Your Homework
Finally some homework to wrap up this week.
Write a formula to find the maximum gap between consecutive Friday, the 13ths in next 5 years, from a starting date in cell C3.
Please post your answers in comments so that we all can learn.
Checkout more Formula Forensics
Once in a while, we take a complex real world (or as in this case, gory world) problem and write an equally scary formula. Then, we go great lengths breaking it down and explaining it. We call this as Formula Forensics. Much like forensics in CSI, without ultra zoom & hot chicks. You can check out some of our recent adventures here:
- Using an array formula to count maximum occurrences of a text
- Counting specific words in a multi-cell range
- Extracting a list of items from a larger list by criteria
- … More formula forensics
PS: It is also Hui’s birthday today. Lets wish him many more years of fun, happiness & Excel craze.
PPS: Finding his next birthday is going to be simple, we just write =DATE(2013,1,13) 😛
28 Responses to “2010 Calendar – Excel Template [Downloads]”
[...] Download and print the calendars today. You can add notes to individual dates or complete … [...] Uni Ego / Free 2010 Calendar – Download and Print Year 2010 Calendar today [...]
Any chance on a 2016 calendar?
Afternoon,
I have one similar calander that I added conditional formatting to so that I could highlight any planned factory holidays. I think i "borrowed" the formula from another calander so I won't post it here.
I also added week numbers to it using the formula =WEEKNUM(MAX(C6:I6)) Where C6:I6 is the range of dates in that give week. It works fine on most of the months but return strange values on other months (Week 6 in October?) I can't see any logic behind why it does this.
Any suggestions for an alternative formula to give the week numbers?
Regards,
William
Hi Chandoo,
I've added a new feature on your spreadsheet.
This control can be useful for all the sheets where you need to check dates.
Cheers
http://cid-69a78592a23a8438.skydrive.live.com/self.aspx/.Public/2010-calendar%5E_Miguel.xls
Hi Chandoo,
Nice calendar.
Till now whichever calendar I saw in Excel, it contained only the outline sheet.
Good to see monthly views and the mini view too.
Liked the mini view much. 🙂
-Nimesh
@William: This weeknum may be because the input dates to max are not properly formatting as excel dates.
Good tip on the conditional formatting and holidays btw...
@Migueal: Now that is super awesome. This is the reason why I love to blog. Readers will always one up me with such cool alternatives. Thank you for sharing this with us.
@Nimesh: You are welcome 🙂
is it possible to get the Notes section on the outline page to display the notes added to the month page for a specific date?
So if you add thing for January 2nd, and then select January 2nd those notes appear on the outline page
@Shish... You can do that using some formula magic. I would not recommend pushing excel to that as outlook / google calendar / icalc etc. do exactly that much more elegantly.
[...] Perpetual Excel Calendar – Free Downloadable Template [...]
Happy christmas to all of you!
This is really awesome. The nicest calender I've seen for Excel. I also like Miguels version of the sheet.
Just one "feature" is missing to me. As I live in Germany - where weeks start on Monday - I'd like to change this. Could someone please give me a hint how to do this?
Thanks in advance
Jörg
Hi Chandoo, I’ve added some new features on your spreadsheet with your permission.
Check it here:
http://cid-6b219f16da7128e3.skydrive.live.com/self.aspx/.Public/Calendar%5E_Pedro.xlsm
Miguel, this calendar is translated to Spanish language.
Jörg, this new approach allows us to start weeks on Monday.
Also it's possible to start weeks on Sunday if you enable Excel macros and push the arrows.
Best Regards,
Pedro.
@Pedro.. superb stuff.. thanks for sharing the file with all of us.
Hi Chandoo, for dates before March 1, 1900 our calendars are wrong.
In Microsoft Excel, DATE, EOMONTH, WEEKDAY functions return an incorrect result between Monday, January 1, 1900 and Wednesday, February 28, 1900.
See this page: http://support.microsoft.com/kb/214326/en-us/
Microsoft Excel incorrectly assumes that the year 1900 is a leap year in all Excel versions.
That's the reason why our calendar versions only work from March, 1, 1900 until December, 31, 9999.
Your comments are welcome.
Pedro.
@Pedro.. Thanks for pointing that out. wow... This reminds me of the Joel Spolsky's first BillG review - http://www.joelonsoftware.com/items/2006/06/16.html (read it, I am sure you would love it.) when Bill out of blue asks about date time implementations for VBA (which Joel is the program manager for...)
Thanks for sharing the URL too... Here is a specially made, chocolate sprinkled, extra fluffy donut for you 🙂
Hi Chandoo, thanks a lot for the donut but I prefer it without chocolate!
Always it's good to know a little history of Excel.
The Joel Spolsky’s last BillG Excel review was about the "Hall of Tortured Souls"
(See this Excel 95 Easter Egg here: http://www.eeggs.com/items/719.html)
Do not miss the humor!
@Chandoo.. I just return with a new calendar version.
http://cid-6b219f16da7128e3.skydrive.live.com/self.aspx/.Public/calendar-pedrowave.xltx
It helped me to practice conditional formatting, formulas to show check boxes, data validation drop down list, find out Thanksgiving Day's date for any year, how to find dates of public holidays using Excel, all reading your wonderful posts!
Perpetual Calendar Spanish version starting weeks on Monday:
http://cid-6b219f16da7128e3.skydrive.live.com/self.aspx/.Public/calendario-pedrowave.xltx
Main characteristics:
- Not macros.
- Select a year from 1900 to 9999 with a dropdown listbox.
- All date fields with the real date format.
- Easy language change of day of the week and month names because are also dates.
- Hide Saturdays and/or Sundays.
- Week starting on Sunday or Monday.
- Week and month numbers.
- Hyperlink between sheets.
- Consistent colors to Holidays, Diary and Events dates.
- Easy change of Holidays by country.
- Include 80 World Days and you can add more.
- A diary with my birthday and 50 more programable appointments.
- Check box to hide individual dates or all.
- Holidays, diary and events text are showed on each month's sheet.
- Ranges defined with Name Manager variables.
I'll appreciate if you make me some suggestions to improve this calendar.
Pedro.
Please, I need help!
I like all calendar from Pedro, thank you for them. Let me show my problem:
I have 2 excel cells (for example AE12 and AE13) which mean the starting and the ending date of my duty. I need a macro to insert sheets with label YEAR. MONTH (for example 2010. August or similar) with the proper datas between the two dates. Is it possible?
Thank you for reading me and sorry about my terribel english! 🙂
Hello Pedro,
Thanks so much for the modified calendar template. I love the extra functionality you added. Is there any way you could upload an unlocked version? I wanted to change some of the comments and data validation so I could use it for one of my applications.
As for feedback on potential improvements, with all the additions you made the file runs pretty slow. I'm sure this has to do with all the interconnectivity between the various tabs, but if there is a way to use less memory via more efficient formulas or something else I think this would make it easier to use. I have a brand new computer and with it running alone the response was pretty slow. One of the changes I'm making is changing the order of the months to match my company's fiscal year, so maybe something to automate a change like that could be useful.
Cheers,
Peter
Peter, my calendars are unlocked but you need Excel 2007 and 2010 versions to open them.
Now I return with a new Programmable Task Calendar:
http://cid-6b219f16da7128e3.office.live.com/view.aspx/.Public/Calendario%20de%20Tareas.xlsx
Wath an introductory video here:
http://pedrowave.blogspot.com/2010/10/programmable-task-calendar.html
This new calendar allows to select the start month to match the school and fiscal year.
This is great stuff Chandoo and company
Wanted to know if someone had built something similar
I need to store one Excel Sheet on this calendar that has all the holidays
US Holidays appear in RED
UK Holidays appear in Blue
Meetings appear in Green
Submissions appear in Orange
Is there a way I can store the list in a separate worksheet and all the calendars get updated with this?
Thanks
[...] Calendars: Year 2010 Excel Calendar | Year 2009 Excel [...]
please tell me "how to convert Rs.10000/- in to words through excel formula
[...] is all! http://chandoo.org/wp/2009/12/11/2010-calendar-excel-template-downloads/ See more Templates at http://www.vertex42.com/ Share this:Like this:LikeBe the first to like this [...]
Greetings,
Thanks for this wonderful excel vacation tracker. I notice that the tracker only has three months November, December and January 2015, however, I would like to add the other ten months for 2014. Can you please instruct me on how I can add the other months?
Thanking you in advance.
Hi Chandoo,
Calendar: can this be printed as single sheet 8.5x11 inch per month
kanu
@Kanu
Yes,
You can resize it to fit
WOW! I just searching some of like this, that help me.
Thank you for sharing.