Recipe to Shopping List

In short Turning recipes into a shopping list means three separate operations, and the second is where it gets useful. First, extract the ingredients and separate quantity, unit and item. Second, combine the same item across recipes — three recipes each wanting an onion is three onions, and the whole point of a combined list is not discovering that at the shop. Third, group by aisle, because a list in recipe order sends you back and forth across a supermarket while a list grouped by section does not. Scaling for a different number of servings is arithmetic on the quantities, with one caveat worth knowing: not everything scales linearly. Doubling a recipe does not double the cooking time, and it usually does not double the salt or the raising agent either. The other practical point is the things you already have. Subtracting your cupboard from the list is what stops the fourth jar of cumin, and it is the step people skip because it means looking.