How many pounds of blueberries do I need for 6 12 cups mashed blueb. for jam?

To make 6 12 cups of mashed blueberries for jam, you typically need about 2 to 2.5 pounds of fresh blueberries per cup of mashed fruit. Therefore, for 6 12 cups (which is equivalent to 6.5 cups), you would need approximately 13 to 16.25 pounds of blueberries. It's always a good idea to have a bit extra, just in case.