Tempus Calendar

Tempus Calendar is an efficient calendar program for Windows. Linux and macOS support coming later.

It supports 3 main calendars (Gregorian, Julian, and Jewish), with more (e.g. Hijri) coming soon.

Tempus Calendar will also calculate sunrise, sunset, dawn, and dusk times based on a given location. This is all done locally - no internet connection is made. Simply put in your longitude and latitude, and the program will do all the calculations itself.

Finally, it will calculate Jewish Zmanim, Islamic Salah, and Christian prayer times.

The project is still in heavy development, and therefore in a beta state, but it is functional enough to be useful.

This project uses SDL2, Freetype, and the Odin programming language.

[Update 2025] Tempus Calendar is now open source! Christian Seibold / TempusCalendar · GitLab

Currently Supported Features

• Gregorian, Julian, and Jewish Calendars can be used as the main calendar display
• Dates for each supported calendar, listed under each day on the month page.
• Sunrise, Sunset, Dawn, and Dusk calculations
• Jewish, Islamic, and Christian prayer times, listed on the Today page.
• HiDPI support
• Zooming interface in/out with Ctrl+ and Ctrl-
• Basic animated interface
• Sundial Time (experimental)
• Time display setting ("24:00" or "12:00pm")
• Holidays
• Creation of events
• Start date and time
• Weekly recurring events
• Name and description
• Editing events
• Monthly, Weekly, and Today views
• [0.3] Holidays for Christianity, Judaism, and Islam, with setting to turn each of them off/on
• [0.3] Jewish Parshiyot, Daf Yomi, and Nach Yomi
• [0.3] Catholic Liturgical Season/Cycle Information

How to Use

To run the program, download the zip file and unzip/extract it to a folder. Then, from that newly unzipped location, double click "TempusCalendar.exe".

On first launch, a screen will popup asking for your longitude and latitude. This is used to locally calculate sunrise and sunset times, as well as prayer times.