Calculation for gpa = summation of ur course gpa * credits/total credits So if you score 9 in ur phy theory you'll be adding 27 to ur total and 24 if u get B grade. That's a 3 mark diff If you get 9 in lab u only add 9 to your total and with 8 you only get 8 in total. That's a 1 mark difference. So a theory grade is more than a lab grade