Plan for as much room as you feel comfortable with taking up in your living space. This question I assume implies a shelter-in-place (bugging in) scenario. Remember, water is the essence of life. One cubic foot of storage space per person for each two days is a starting point for planning for water. One cubic foot of water is about 7 gallons IIRC. You may want to go higher. Play around with various foods to see how much storage space a day/week/month's worth takes up. I am in the middle of preparing for a move from OK to Upstate NY so I can't offer any guessitmates.

Last thing: don't forget to plan for the pet's needs if it applies.

My 2 cents.