The "Grades" option is disabled in iStudiez Pro by default.

Go to the Settings/Preferences of the app to enable the option.


iStudiez Pro can handle three types of grading scales:

Percents

Using Percents as a grading scale, your GPA will be calculated based on and reflected as percents.
Enable GPA Scale option to use custom GPA Scale (you can tune it).
Otherwise Overall GPA will appear as percentages.

Editing the scale please avoid overlapping values (e.g. 85% - 90% = 3.70, 91% - 100% = 4.0), otherwise your GPA will be calculated wrong.

Letters

This grading scale allows converting percents into letters based on the customizable matching scale.  
Once you set up Letters as a grading scale, you are offered to choose one of five default grading scales (e.g. A-F, A-F(+/-), etc.)

You can customize grading scale according to the one used in your institution and it will be saved as Custom scale.
Furthermore, the scale may be tuned for any course as well.
Go to the Planner > Semester > Course > Grades > Grading Scale > edit the scale.

Editing the scale please avoid overlapping ranges (e.g. 85% - 90% = B, 91% - 100% = A), otherwise your GPA will be calculated wrong.

Points

Points as a grading scale is used mostly in European countries, for example in Germany, Norway, etc.
With this grading scale chosen, you can set up points range according to your education system, e.g. from 6 to 1, or from -2 to 6.

If you get your grades in 'points' (e.g. 20 out of 25) you'd better use Letters or Percents.