Many universities request that students who have studied outside of the U.S. submit a credential evaluation or course-by-course evaluation from an external credential evaluation service. While these evaluations are expensive they can be beneficial, especially if you are transfer student.
Education systems vary throughout the world and in some countries the grading scales vary from university to university. Most university admissions offices have a trained foreign credential evaluator on staff who can determine international course and degree equivalencies. If you are requesting that courses from your home institution be transferred to a U.S. institution, this will require a good deal of background knowledge and research on the part of the foreign credential evaluator. International university information is not always easily available in English and it is also very difficult to ascertain the number of hours you studied and the academic content of the course to determine if it is equivalent to any coursework available at a U.S. institution.
Universities generally do not award transfer credit if there is any doubt that the course may not be equivalent to the course offered at their school. A credential evaluation service can help clear up any doubts by doing the necessary research and providing a course-by-course evaluation with information and a recommendation on how the university should proceed with awarding credit. The final decision rests with the university.
If you are asked to submit an outside evaluation, be sure to confirm with the university if they recommend or require any particular service or if they have a list of approved services.
While there are many certified evaluation agencies, here are links to three of the most widely recognized: