I have a recipe that calls for 5 tablespoons of milk but only have powdered milk. And i don't want to make more than what I need as it won't get used in this house.
Five tablespoons is a smidge under 1/3 of a cup. There are four tablespoons in a quarter cup.
You don't say what the reconstitution percentages are for your powdered milk but if you do whichever conversion is for 1/3 of a cup, you should be fine. Most recipes don't need it to be absolutely exact. A little extra milk isn't going to harm anything.
Please note, depending on what you're using this for, you may need to add fat of some sort unless you have whole milk powder, as many powdered milk products are non-fat. Most recipes that call for "milk" mean "whole milk" substituting fat free milk (skim) can be detrimental to the final flavor of the milk.