Per Bastemhet

Kemetic Calendar

with 28 comments

This post I intend to be a gigantic compendium of all the research I’ve done on the ancient Kemetic calendar.  By reading this one should be able to create their own calendar with accurate festival dates for their area, or configure a fixed, ideal calendar that will line up with our current Julian calendar. (note as of July 31: this is by no means complete information.  What I’m doing as of now is using the HoN calendar [which is a hybrid calendar and not the same as an ancient calendar] and one can calculate wep renpet in part III- this is convenient because they also calculate with leap year in mind, unfortunately it’s only available to members.  You can also use Kerry Wisner’s calendar for the same purpose.)

Table of Contents:

I. Special problems of the Kemetic calendar

II. Fixed ideal or unfixed traditional?

III. How to create your own traditional calendar with the wandering year

IV. How to create an ideal, fixed calendar

V. Festival dates and other helpful information


I. Special problems of the Kemetic calendar

One thing that you should know about the Kemetic calendar(s) is that there was more than one, and the dates are not fixed as they are in the Julian calendar. There was a solar calendar, which was also called the civil calendar, and would mark all days beginning with wp rnpt on the first day of the year. However the first day would change, unlike in our Julian calendar. The reason why this is is because the date of the new year (wp rnpt) is determined by calculating when the first time Sirius (Sopdet) is visible in the sky before the sun rises. To learn more about Sopdet’s role you can refer to Jeremy Naydler’s "Temple of the Cosmos" page 67-73. The lunar calendar was the religious calendar with all the festivals listed in it.  This calendar was rarely ever in synch with the solar calendar, because the lunar month cycle only lasted 354.7 days while the solar month cycle lasted about 365 days. (not 365 1/4 like in the Julian calendar)

There are other problems if you decide you want to research this yourself.  Some of the best Egyptological calendar studies are in German, so if you don’t speak that language you are limited in what’s available to you.  Also, besides there being two calendars, Egypt was a big place.  The new year started at different times depending on the visibility of the rise of Sothis, and so naturally the festival dates would occur at different times in different areas.  We also account for the difference in dates because sometimes festivals would include the travelling of the idol down the Nile by barque, and so the celebration of the festival would be on different days depending on when the idol arrives.  One example of a prolonged festival including the travelling of idols would be the Festival of the Beautiful Reunion

Also, not all the calendars are complete.  The one that is preserved the most is the calendar at Medinet Habu.  Some festivals appear on some temple calendars while they don’t appear on others.  There is no reliable, consistent data as far as modern temples go because there is no reliable, consistent source data.  If any temple tells you a festival is on a certain day, you should ask yourself, “Based on what festival calendar?  And based on what location for the rising of Sopdet?”  A modern temple should have well thought out answers to both questions, as both are up to personal decision.

There’s also the problem of the Kemetic calendar being based on a three season system while (at least in the U.S.) we are based on a four season system, and if it makes sense to have a harvesting festival when your current location is in winter.

For another explanation that mentions a lot of the things that I did, read this.


II. Fixed ideal or unfixed traditional?

You will have to figure out if you want to keep the flawed system of days so that the calendar would be off every by a day every 500 years.  If you do decide to make an "ideal year" calendar so that the year would be the same every time rather than depend on astronomical events, you will have to understand that the Egyptians probably would have seen this as absolutely wrong, and whether you are OK with that.  Each day in the lunar calendar was considered sacred, as we see in representations of the calendar with each month and day being depicted as a deity.  There must have been a reason to not change this for thousands of years. 

The years that include the 13th intercalary lunar month are called great years.  The great years fall on the 1st, 3rd, 6th, 9th, 12th, 14th, 17th, 20th, and 23rd year of each 25 year cycle. (this sequence based off of papyrus Carlsberg) The lunar calendar has a lag of .04769 day every 25 years.  In 500 years that would amount to one day.  In order to continue your calendar from the Kemetic one, you would need to figure out when the last time the 25 year cycle ended, and you would also need the astronomical data from the location in Kemet that you are working from.  This is assuming you’re basing it off of data from Kemet.  I can’t even figure out how you would need to adjust the data if you’re basing it off of a different location.  Let’s face it: I have no astronomical training and I was never that great at math.

There are reasons for either keeping it traditional (or at least, as traditional as possible) and reasons for creating an ideal calendar.  I’ve heard those that are up to the task of calculating every new year and every time an intercalary month would be needed explain it this way: adopting an ideal, fixed calendar would have to rely on Alexandrian modifications, and this is not in line with pharaohnic tradition. 

As for not calculating it every time, I think that while it might be wrong to alter the dates of the spiritual days as I’m sure they had spiritual significance to the ancients as they were (they did keep a semi-flawed system for thousands of years), I also consider this a small concession to the whole "reformed" aspect of my personal Kemetic practice.  Besides the relative ease of having to add only one day a year depending on if it was a leap year or not, the change has significance for me as well. For the ancient Kemetics, their Beloved Land had symbolic significance, as is described in Naydler’s "Temple of the Cosmos." The land of Kemet was also the place where Zep Tepi (the first time of creation) occurred. Kemet is the source from which the wisdom of the gods come, the place Ra first created, the place they chose to live above all other places. While I do love where I live, I have no such spiritual connection to it as I do to the land of our Kemetic akhu. This is why calibrating it to Cairo would be significant to me.

There are things that make sense for me that don’t for other people, and vice versa.  While I agree that both decisions have merit (and I surely give props to those who are willing to do the work of the calculations and staying on top of that), I think that I would rather have more people celebrating the holy days (even if they might be a week off) than be turned off by the whole "astronomical calculation" aspect and just give it up.  In the end, it’s up to you. 


III. How to create your own traditional calendar with the wandering year


The following information on how to calculate when the heliacal rise of Sopdet will be visible from your location is provided thanks to the Temple of Ra based in San Francisco, CA:

To figure out when Sopdet will rise before the sun, you will need the longitude and latitude of your location, and the number of hours east or west of your location from Greenwich. Make sure the number has not been adjusted for daylight savings time since you will be readjusting new year’s day every year, which discards the necessity of daylight savings time.

Enter in your information for the sun, as well as the dates between late July and mid-August, and copy and paste this with a word program on your computer. Then go back and enter the same information, but do it for Sirius. Put this information in the same area as the first information. Now you will want to look for the first time that Sirius rises before the sun, i.e. before civil twilight. This date will be the date of wp rnpt.

Click here for the astronomical website:


Now that we have the date of the solar new year out of the way, we have to figure out when the lunar new year begins since it starts on a different day than the solar new year (remember the lunar month cycle is shorter than the year of 365 days). The following information on how to account for the new day of the lunar new year was taken from the INK Library, specifically from an article that Kerry Wisner wrote:

1. The lunar year begins with the first New Moon following the heliacal rising of Sirius (the first appearance of Sirius on the eastern horizon at sunrise).
2. Whenever Sirius rose helically in the last eleven days of the twelfth month of the previous lunar year an intercalary (additional) month was added to the new year. This thirteenth lunar month was called Djehuty (Greek name: Thoth) and was added at the beginning of the new year. This was done to avoid having the festival of Wep–renpet, "Opener of the Year" (the rising of Sirius) from falling into the first lunar month of the next year. This thirteenth month would need to be added approximately once every third year.
3. Whenever the first day of the lunar calendar would fall before the first day of the civil calendar, the intercalary (additional) month was added.
4. A lunar week consisted of the time between each of the four phases of the moon, approximately seven days. Each lunar month was named after a specific Egyptian Goddess or God to whom it was dedicated, or after a major festival that occurred during that month.

And here is some further information that I learned while reading The Calendars of Ancient Egypt by Richard A. Parker:

1. Any time the 1st day of lunar Thoth fell before the 1st day of civil Thoth, the month was intercalary.

2. The schematic year would be divided into 12 mos., 30 days each, with the extra five days being an abbreviated intercalary month that headed the lunar year whenever it occurred.

3. In order to keep the calendars at the same time, every second or third lunar year must have 13 mos.


IV. How to create an ideal, fixed calendar

The Coptic Orthodox Calendar is based on the ancient Kemetic calendar and they fixed the difference in dates by following the Alexandrian reform to add a 6th epagomenal day to ameliorate for the sliding calendar.

What this means for you: in Cairo Wp Rnpt is on July 25. Every time. No more calculating. Cairo is a good place to choose also because that’s where the Pesedjet with Ra as creator (the one we are probably most familiar with) was based in. This means the lunar new year starts on the first new moon after July 25, which will vary depending on the astronomical data of that year.

Since we already figure out the day of Wp Rnpt above, we can just add a sixth day upon the year at the end of the year to the calendar every four years, rather than having to calculate it every year. The next leap year (year in which there will be 6th epagomenal day) is in 2012.

Relatively simple, isn’t it?

V. Festival dates and other helpful information

There are many sources for festival calendars.  Here are a few I’ve seen mentioned:


  • Eye of the Sun by Kerry Wisner, offered by the temple Akhet Hwt-Hrw.  The calendar is based of off a year that is 365 1/4 days, so be aware of this if you’re making your own calendar based on your location.  It does come with explanations of festivals and lots of other information.
  • The Ancient Egyptian Prayerbook by Reverend Tamara Siuda.  The dates are based off of the temple’s location in Chicago, Illinois.  Apparently there is a discrepancy between what’s printed in the book and official temple calendars sent out by e-mail to those who have gone through the beginner’s course, as explained here.  There is also information on the KO way of celebrating festivals here, although do be careful since it’s a wiki and anyone can edit it.
  • Temple Festival Calendars of Ancient Egypt by Sherif El-Sabban.  I have a copy of this, and much of the information is a lot of offering lists, while it doesn’t necessarily cover the meanings of every festival.  However we do get a good selection of temple festival calendars. 
  • Ancient Egyptian Magic by Bob Brier.  I’ve heard this book recommended for its Cairo calendar, but not so much for the rest of its content.  (For a better, scholarly book on Egyptian magic that is free as a pdf, check out The Mechanics of Ancient Egyptian Magical Practice by R.K. Ritner, or Symbol and Magic in Egyptian Art by Richard H. Wilkinson)
  • Feasts of Light: Celebrations for the Seasons of Life based on the Egyptian Goddess Mysteries by Normandi Ellis.  I haven’t read this but it was suggested by someone else.
  • The Calendars of Ancient Egypt by Richard A. Parker.  This has proved to be one of the most helpful books on Egyptian calendars I’ve read, but it’s not for the weak.  It’s a scholarly publication with a lot of information, not all of it relevant to the modern day creation of calendars.  The link takes you to a free pdf copy.

There are other books I can think of but they’re out of print, academically dense, not necessarily in English, and extremely expensive. 


I hope this was helpful!  If you have any lingering questions, don’t hesitate to comment and I’ll do my best to help you find the answer.




Written by Bastemhet

June 24, 2011 at 2:06 pm

28 Responses

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  1. I am pleased to discover that other European interest in the problem of re-building of the Egyptian calendar. I am also interested in the subject with French Kemetic (forumboards S.E.M.A.T. ANKHTY).

  2. I recommend this book “The Egyptian calendar: an eternity of work” written by Anne-Sophie von Bomhard, which explains the different calendars (calendar, lunar, solar) and how they work.

  3. Okay, so, I’m really trying to create an ideal calendar and I think I’m going to base it off of the Coptic calendar you mention above. However, the issue I’m having is that I want to create my calendar based off of the ancient center of Memphis, as opposed to Cairo. Do you have any idea where I could find the information I desire for Memphis: time zone, lat/long degrees, minutes, and seconds?

    Aubs Tea

    July 10, 2012 at 4:21 pm

    •,_Egypt This will show you the lat/long, and it´s only 12m south of Cairo, so I´m assuming it´s the same time zone. Good luck with this! Why Memphis though?


      July 10, 2012 at 8:06 pm

      • I chose Memphis because someone pointed out that it was one of the main religious centers throughout the epochs of ancient Egypt and that never really changed. Also, it’s the home of the Sekhmet’s triad, so it’s also like an homage to her. XD

        Aubs Tea

        July 11, 2012 at 2:23 pm

  4. […] Post Kemetic Calendar by Bastemhet. Share this:FacebookEmailTwitterLike this:LikeBe the first to like this. Posted in […]

  5. I’m so confused. I really can’t figure out if I’m doing the calculations right. Would you be willing to help me?

    Aine Rayne

    August 12, 2012 at 7:02 am

    • Sure! What´s your question?


      August 12, 2012 at 2:04 pm

      • well, I used the links you provided to find the rising of Sopdet before the sun and I thought I was doing it. Just to be sure, I did the same with Memphis to see how Aubs got July 25th for her date. I’m doing mine from Hardai btw, it’s in Minya. Honestly I don’t see how she got the 25th at all, the numbers don’t add up and I don’t know if I’m doing something wrong or not

        Aine Rayne

        August 12, 2012 at 9:47 pm

    • My Wp-Rnpt is actually the 30th. XD I just wanted you to know in case that was a source of your confusion.

      Aubs Tea

      August 12, 2012 at 10:40 pm

  6. Aine Rayne: When you put the info in make sure you are putting it in exactly. For example:

    I just checked for Memphis and Wp Rnpt should be July 30. I have no idea, though, whether it should be moved back and have an intercalary month since this is a leap year. It might be possible. I would ask Aubs what she did.

    Make sure when you put the coordinates in that you indicate if the Longitude is east or west, or if the Latitude is north or south. You also need to click on whether the time is east or west of Greenwich. You can use this link to get the standard time (not adjusted for leap years) here:

    Try again, and if you still can´t get it to work, I can do a step by step for you for the Hardai date.


    August 13, 2012 at 8:16 am

  7. […] As taken from the Temple of Ra (based in San Francisco, CA) (and also as found/recommended on the Per Bastemhet Kemetic calendar post): […]

  8. Reblogged this on The Darkness in the Light.


    July 6, 2013 at 10:43 pm

  9. […] Here is a great post about Kemetic Calendars by Bastemhet: Kemetic Calendar. […]

  10. […] of specifically how and where you go about this information. I will, however, provide a link to the entry that helped me with this. Suffice to say, this is probably the most labor intensive (and I don’t recommend doing it […]

  11. […] Kemetic Calendar: Per Bastemhet […]

  12. […] placing the first day of the current Kemetic civil year on August 9th, 2013.  I used this site to help me determine the structure and start date for my Kemetic calendar.  I plan on laying out a […]

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