The number of credits usually depends on the course period. Also the exact number differs for each course. You can find the exact number of credits on the course page. Those are ECTS credits, guaranteed by Utrecht University or HU University of Applied Sciences.
It depends on your own university, however, whether the credits are accepted. If you want to be sure about that, please contact your own study advisor or international office. He or she can always contact our course leaders, in order to learn more about the content and the level of the course. The course leader will provide an official Utrecht Summer School certificate on successful completion of the course.