There are 0.5 cups in 4 ounces of water.
To convert ounces to cups, divide the number of ounces by the number of ounces in a cup, which is 8. Therefore, 4 ounces is equal to 0.5 cups.
Keep in mind that the size of a cup can vary depending on the measurement system being used and the type of ingredient being measured. For example, a cup of liquid ingredients will typically measure 8 fluid ounces, while a cup of dry ingredients will typically measure 4.5 to 6.5 ounces.
It is always a good idea to check the label on your measuring cups to ensure that you are using the correct size.