I found this...
For cooking, a smaller sugar or pie pumpkin (usually weighs between 3 to 8 pounds) is more flavorful than a larger carving one. One pound of fresh pumpkin yields about 4 cups raw peeled and cubed, or 1 cup cooked then mashed or pureed pumpkin.
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How many cups is a small pumpkin?
Fifteen ounces of canned pumpkin is just shy of 2 cups (16 ounces would be 2 cups). A 3-pound pie pumpkin will likely give you enough puree for your recipe.