You can, in fact, not be completely sure. There is no generally recognized reference grid to compare ECTS credits with other evaluation systems. We can only recommend to be guided by the ECTS regulations applicable to Erasmus students or other foreign students at your home university. Please contact your examination office or info service for foreign students to find out how many credit points are awarded to them for individual courses.
ECTS (European Credit Transfer System) is a European evaluation system that does not only consider the exam result, but also the workload associated with a particular course. For 30 hours of work (per semester) 1 ECTS credit is granted. Hours of work include the time spent in class, the time spent for preparation and follow-up as well as the time for exam preparation, if applicable.

We recommend that you ask your previous university for a document which specifies the local credit system and regulations for conversion into ECTS points or work hours. Please add this document to your application in order to avoid errors in credit conversion during the selection process.