The go-to ratio for making jello shots is 1/2 cup of booze per three ounces of jello mix. But, let's be real here, the standard ratio is more like a suggestion, not a rule. If you want your shots to be a little more tame, go ahead and use 1/3 a cup of liquor instead.  Just remember to increase the cold water amount so that you're always using 1 cup of cold liquid in total. On the other hand, if you want them to pack a real punch, you can use one cup of liquor instead (and omit the cold water). It's all about finding the right balance flavor balance between the jello and the strength of the alcohol. Experiment with the ratios, and don't forget to party responsibly.