On the mixing pail, the measurements are marked on the lefthand side of the cup and the ratios are marked at the top. After you determine how much primer you are going to mix, you must find out how many parts primer need to be mixed with how many parts activator. It is marked on the paint can. Ours called for 3:1, meaning three parts primer to one part activator. So we filled the pail with primer to the first line marked with a three (see the Car Craft finger) then added the activator to the next line marked with a three. Simple.