Creator of the Symmetry454 CalendarThe Kalendis Calendar Calculator (Free)

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Created by Dr. Irv Bromberg, University of Toronto, Canada email icon

[Click here to go back to the Symmetry454 / Kalendis home page]

The freeware Kalendis computer program allows users to interconvert any dates using any combination of the following calendars:

Kalendis also computes the difference between any two dates or moments (in days or in days and fraction of a day), finds solar birthdates and anniversaries, yahrzeits, omer counts, displays many of the secular and religious holidays and other special days and events associated with each calendar, and computes various time and astronomy values such as sunrise, sunset, monthly twilight and astronomy reports, Bahá'í daylight fasts, Easter comparisons, monthly zmanim reports, moladot, Hebrew possible weekdays, equinox, solstice, solar longitude, lunar phase, and the bearing and distance between locales, etc.

Kalendis has the unique ability to carry out its calendrical and astronomical calculations in terms of the days elapsed relative to any desired epoch, and the user can change that epoch at any time, quickly and easily.

Kalendis is compiled as a Windows executable application, but it can run under intel versions of Linux using WINE or under intel versions of MacOS X using CrossOverMac.


Click here for extra explanation if you are a user of Linux or MacOS X.

Windows users, click here to download the full Kalendis installer for Windows 2000 / XP / Vista / 7 / 8.

Download file size about 3.2 MB, version 9.856(1576), revised Nov 22, 2014 (Symmetry454) = Nov 20, 2014 (Symmetry010).

Click here to see the Kalendis release notes (what's new in this version)

You must be logged in as an administrator, otherwise your system won't allow you to install or uninstall software.

If Kalendis has been previously installed then before running the full installer use the Windows "Add/Remove Programs" control panel to remove the old version.

After downloading the installer, launch it by double-clicking on its icon. It will create a temporary directory, self-extract the files that it needs, carry out the installation, and then remove the temporary directory.


Please come back for updates -- check the version numbers and revision dates, as well as the web site news.

To learn the features of Kalendis just hover your mouse pointer over various objects and read the displayed "tool tips". Also read the "About..." and calendar information dialogs. Use the built in "Kalendis Home Page" command to check back here for updates.

If you want to carefully position the various windows to your preference, but find it too frustrating to use the mouse to nudge each window into position, then use the built-in Windows MouseKeys feature (see Windows Help for instructions). Kalendis remembers its window state and position between sessions.

Display requirements: Works best on 1024x768 or larger displays. Kalendis can work with smaller displays, but some scrolling may be necessary, depending on how many calendar windows the user choses to display.

Navigate between dates using the buttons in the Kalendis time and astronomy window (the one that has the currently selected locale information as its title) or your keyboard up- and down-arrow and PageUp and PageDown keys. Use the "Step" menu to set increment size. Kalendis uses the actual mean synodic month to step by lunar cycles, and multiples of the actual solar year or the mean orbital year for all larger steps. The numeric keypad plus and minus keys always step by days. Clicking on any date information copies it as text to the system clipboard, from which you can paste the text into any other application.

You can select from any of the built-in locations on the "Locale" menu, or create up to five user-defined locales. Kalendis remembers the chosen locale between sessions. Click here for a list of servers that can help you find coordinates for user-defined locales.

If you don't care about a certain calendar, just close its window. Use the "Window" menu to choose which calendar windows to display. Between sessions Kalendis remembers which windows were open and where their arrangement on your display, unless you quit with resetting all preferences. Some calendar-specific menu commands are disabled while the corresponding calendar window is not open.

Known minor problems and limitations:


This page updated 27 Cheshvan 5775 (Traditional) = 27 Cheshvan 5775 (Rectified) = Nov 25, 2014 (Symmetry454) = Nov 23, 2014 (Symmetry010) = Nov 20, 2014 (Gregorian)