GPA for other grading systems

I wanna calculate my GPA using a grading system other than letter grades (my school uses advanced/proficient/developing/not yet scale) and our school has guidelines that’ll determine what overall letter grade a student gets at the end of each quarter (each class has outcomes, and each outcome grade is an average weighted by recency of each individual grade in that outcome). could there be a feature that’ll predict this and convert that into a quarter letter grade and use that for gpa. lemme know if I need to be more specific, because idk how to explain this well