A standard dining table size is generally considered to be 66 by 36 inches or 168 cm long and 90 cm wide. This may comfortably seat 8 but maybe a tight squeeze for 10. Generally speaking, the bigger your dining area, the bigger you can go with your dining table size. This is because when you have lots of space, people tend to congregate at one end rather than spread out in a line along its length.
Tables that serve 12 or more people fall into the large dining table size. Some homes choose to use a very long trestle-style table in their dining areas where people sit on each side instead of an extension leaf design which allows both ends to be pulled out for extra seating when required. In this scenario, care needs to be taken with the design of the table to ensure that it has enough strength to take the weight of people leaning across it. On some, the dining table size can be extended from a 2-seater up to an 8 seater, but if you are looking for more flexibility then you may want to consider some folding or stacking chairs that tuck away under your table when not in use.