oats hydration

I have a recipe for a basic sandwich loaf that uses rolled oats that I'm trying to play around with, but to do some calculations I want to figure out what my starting hydration is.  If the recipe has about 3cups of flour and 1 cup of oats, how do I calculate the hydration?  I can weigh them at home (I'm not there right now, so I'm not sure how much the oats weigh), but I'm pretty sure I was using 15.5oz of flour and 10oz milk.