There are different opinions on how much water you need.  From a recent article on pbs.org, the easiest way of calculating how much water you need (per day) is to take your body weight and divide it by two.  The number you get is how much water you should drink in ounces.  If you want to know how many cups, then divide the ounces by eight ( if you get a number with a remainder round up).

Don’t worry there is no more math.