Just in case there are others with as little info on paint mixing, thought I'd pass along a recent experience. I bought a quart of my selected color to do a very small area to see if I liked that color. It worked fine so expecting an expert painter soon, I headed to the paint department of one of our box stores. The paint code was on the lid of the quart can so I showed it to the young man behind the counter. He mixed up the paint for me seemingly without problems. The painters first question, did you mean to use two different colors in here? Puzzled I returned to the store. It seems that the code for quarts is always different than it is for gallons! Learned the hard way and wasted several days in the process.