Nerv, simply put the ratio is the amount of one substance compared with the other. I'll keep it simple. To mix color "x" I'm told to use 3 drops of color "y" and 2 drops of Color "Z". My ratio is 3:2
Doesn't matter the size units you are using either as long as you maintain the ratio. Whether it be 3 drops or 3 gallons. Its the same. Hope this clears things up for you. "Q"