*To have the correct ratio of sugar, thickener, and blueberries that I've used in this recipe, you need 800g of fresh blueberries which is about 5½ to 6 cups of blueberries. If you don't have a scale and forgot to weigh them before leaving the store, there is a way to eyeball how much water content your blueberries have. If they are juicy to the taste and on the larger side, they have more water so use 5½ cups. If they are smaller and don't taste as juicy, use 6 cups.