The Sith do not mark time from the Battle of Yavin, as the New Republic does, but instead have defined three distinct eras of Sith History. However, for the benefit of those using that calendar, a quick summary is given, to allow for translation from Sith calendars.

The first era begins with the foundation of the Sith Empire, approximately 24,400 before the Battle of Yavin. For any date marked SE, subtract that number from 24,400 for the BBY date.

The second era begins with the first revival of the Sith Order, approximately 4400 years before the Battle of Yavin. For any date marked SO, subtract that number from 4400 for the BBY date.

The current era begins with the foundation of the Galactic Empire, 19 years before the Battle of Yavin. For any date marked GE less than 19, subtract that number from 19 for the BBY date. For any date marked GE of 19 or greater, subtract 19 from the date for tha ABY date.

Hopefully this will address any confusion regarding dates in various discussions of Sith history.