Most interior designers will tell you to leave at least 36” from the ends of the table to the wall or any other furniture piece like a buffet table. Essentially, measure the length of your room and subtract 72”. That will give you your maximum table length.
Most standard dining chairs are approximately 20” wide so we typically say to allow 24” for each chair at your table, but keep in mind that chair widths vary. Take a look at the diagram below to help you get started on deciding what length works best for you and your space.
Please note: These are just guides, your table size may spacing may be determined by chair size.