1) Add up total innings pitched 2) For every out while you are pitching, you get one-third of an inning. 3) Add up the total number of runs during your innings pitched. If there are no errors in the inning, all runs are earned runs. If there are any errors, 4) Multiply the earned runs by 9 5) Divide by the total innings pitched 6) Round the number to the second decimal place. For example, 3.54332 is 3.54