This article contains a chart of how much vegetable crop needs to stored for a family of four.
It is based on the experience of the writer (Katherine Grossman of the Granny Miller website).
Obviously your mileage may vary, but the author has more than a little credibility in this area.
http://granny-miller.com/a-garden-planner-for-home-food-preservation/You can adjust the numbers for the size of your family.