It is self reported, but that doesn’t make it wrong per se. Wikipedia is all “self reported” but it’s accuracy on most things is decent.
However, if it’s available at your school the best guide, in my opinion, is Naviance as it shows the grid specific to applicants from your school and none of it is self reported. It still leaves out a lot of factors that matter a lot to admissions (legacy status, athletics, ethnicity, etc…) but it is an excellent guide.
I hope these are correct because if they are I have a good chance of acceptance even with a 3.4 gpa. Most people at CC are a bit pessimistic when it comes to “chance me” threads if you ask me, thanks for the response