Approximately six medium peaches are needed to make 4 cups of sliced peaches. Six medium peaches is about 2 pounds of peaches. If using frozen fruit, about 40 ounces of peaches are need to make 4 cups of sliced peaches.
If the peaches are larger, two peaches can equal a pound, which in turn is equal to 2 3/4 to 3 cups of peaches. In that case, three to four peaches may be sufficient to make 4 cups of sliced peaches.
Nectarines or apricots can be substituted for peaches, as well as mangoes or papayas, though that gives the dish a slightly different flavor.