This distribution is a discrete distribution on 5 categories, so it can hardly be called a gaussian distribution. However, the shape is gaussian-like and it is easy to see that the European Union got the idea from the Gaussian distribution. In a very perfect world, the transformation is the same in all countries and

for all tests. For example:

50–60%=E,
60–70%=D,
70–80%=C,
80–90%=B, and
90–100%=A - and then

the grades will approximately have a normal distribution with mean 75% and standard deviation 11.4%.

Besides the ECTS-credits, the European Commission defined an ECTS grading system, as well. Since there are nearly as many different grading systems as countries, its aim is to make grades more comparable to each other.

The ECTS grading system is not replacing the local grading systems, but it’s meant to be a supplement to local grades, for example, on a transcript of records.

Similar to the American grading scale, the ECTS is based on the class percentile. That means that the grade shows how a student performed compared to the other students in the same class.

Before the evaluation, the results are divided into two subgroups: pass and fail. Therefore, the results are independent of the students who failed a course. The grading system is defined as follows:

A: Best 10%
B: Next 25%
C: Next 30%
D: Next 25%
E: Next 10%
FX: Fail (almost passing)
F: Fail