Tables for a formal dining room, informal dining room, or kitchen need to be large enough to allow adequate "elbow-room" for comfort without crowding. Allow 24 to 30 inches per person and at least 30 inches across the table. Standard dining height is 29 to 30 inches.
Check leg placement on any table that will be used for seating. A leg at or near each corner, a center pedestal, multiple pedestals, or trestles are stable and common. Complex and artful shapes also work well, as long as the leg placement doesn't interfere with comfortable seating. Lean on the table from all angels to see whether it tips or wobbles.
Dining chairs should have fairly upright backs, so that diners can sit comfortably close to the table and still have the support of the chair back.
Avoid chairs with legs that splay out widely. They fit awkwardly at the table and are easy to trip over, and they may be weaker than other chairs.
Slide chairs up to the table. Chairs and table should fit easily. Arms should be low enough so that the chairs slide under the tabletop.
Determine whether there is adequate space between the apron (the skirtlike extension around the underside of the table) and your thighs. If you decide to use lower chairs because of the apron depth, check that the chairs are still high enough for dining.