We figure $100 per adult per week for groceries. That means food only, No paper goods, cleaning supplies or other things you might pick up at the supermarket while shopping. We figure about $75 per child under Bar/Bat Mitzvah age when they spend vacations and the summer with us. This includes non-alcoholic beverages.
We buy no prepared foods and cook from scratch. We also live in a country like setting that affords us a large garden where we grow fruits and vegetables. We do can/freeze/pickle our harvest.