The minimum width of your dining table will depend upon how the table will be used and how many guests you intend to place around it. Table shape is also an important consideration in determining width allowance. If your dining table is primarily used for formal family occasions, you will need to provide more central space to accommodate serving platters and dishes. A dining table put to everyday family use as an eating surface and/or workspace may not have to be quite as wide.
The physical space allotted for dining will obviously affect table dimensions. There must be enough room to comfortably pull out a chair and move around the room once guests are seated. Plan for at least 36 inches clearance between the edge of the table and the wall or furniture in your room. If your space allows, 44 inches is optimal. Wheelchair access requires 54 inches. Once the available room space is determined, you can select a table that will fit.
Informal dining does not require space for serving dishes and place settings. A table may be as narrow as 30 inches and still allow enough space for place settings. Formal dining tables average 36 inches in width and may stretch to 48 inches and still allow for the passing of food across the space. Wider tables require that items be passed from diner to diner around the table. A dining table that doubles as a workspace may need to be wide enough for your books, papers and laptop; 36 inches and above should suffice.
Table Surface Allotments
Allow each guest a minimum of 24 inches of table surface directly in front of them. For more comfortable dining, stretch the per person allowance to 30 inches. With rectangular or square tables, remember to add 12 inches at each end to accommodate guests at the head and foot of the table. If your table is round, allow 30 inches per person, as each person's space is reduced towards the table's center. Oblong or oval tables will provide more seating than circle, square or rectangular tables.
A 40-by-40-inch square table will comfortably seat four diners. A round table with a diameter of 36 to 44 inches would accommodate the same number. For oval or oblong-shaped tables, a formal place setting is about 24 inches wide and an informal setting allowance measures 18 inches. Restaurant designers plan for a minimum of 29 inches from an adult diner's nose to that of his neighbor and a space of 12 inches between dining chairs.