In an RTL language, in what direction should calendar days go?

1. How does RTL text work?
2. Which language is RTL?

How does RTL text work?

As the name implies, RTL languages such as Arabic and Hebrew read from right to left rather than left to right (e.g., in English, French, Spanish, German, etc.) The most challenging aspect of RTL localization is that most English content comes in formats that don't support RTL text.

Which language is RTL?

Arabic, Hebrew and Persian are the most widespread RTL writing systems in modern times. As usage of the Arabic script spread, the repertoire of 28 characters used to write the Arabic language was supplemented to accommodate the sounds of many other languages such as Kashmiri, Pashto, etc.