Spinach is about 90% water, so when cooked, it loses a huge amount of volume. The yield will slightly differ depending on the leaf size, variety, whether chopped and how it's packed into the cup. One pound (16 ounces) or about 12 cups of packed fresh spinach wilts down to about 1 1/2 to 2 cups cooked. Approximately 1 ounce (28 grams) of baby spinach is ¾ cup packed before cooking.