% of set value

Hi all please help. I have been given the task of calibration of all of our torque wrench. What I have to do is test the wrench 5 time at various setting i.e 5 times at 80Nm 5 times at 50Nm etc but for each time i have to recored the result within a tolerance of + or - 4% of the set value. What I want is a formula for a cell that calculates the tolerance and dispalys result in red for fail green for pass. My thinking was use conditinal format but Im unsure if you can use % for that. Please any ideas