Effective Field-Goal Percentage (eFG%) accounts for the fact that 3-pointers are worth an extra point, something ignored by traditional field-goal percentage.

Why is this important? Imagine a situation where one player shoots 6 layups, and makes 3 of them, while another player shoots 6 three point shots and makes 2 of them. Both players have scored 6 points on 6 shots, yet the first player’s FG% is 50%, and the second player’s FG% is only 33%. The second player looks like a terrible shooter even though he has scored just as many points on just as many shots! Effective field-goal percentage corrects for this by accounting for the extra point that 3-pointers are worth.

The formula is:

eFG% = (FGM + .5*3FGM) / FGA