Your choice of a dine-in kitchen, full dining room or both will also help determine the size of the house you choose. Dine-in kitchens are typically designed for small or average-sized families because of their convenience.In comparison, full dining rooms are typically used for larger or more formal gatherings. Depending on the age and layout of the house, a dining room may seat six or more people.If you have a large family or frequently entertain, a separate dining room may be a necessity. The average standard dining room is 224 square feet, so this will influence the size of the house you purchase.