If you don't remember your high school geometry, now is the time to review to determine which seat more people, round or long tables. The basic measurements for your computation are for your place settings. You should allow per setting either 60 cm (24 inches) --- doable but a little crowded, or 75 cm (30 inches) --- comfortably welcoming. Also, consider space in the middle of the table for serving dishes and room between the walls and the seats (45 cm (18 inches)) for guests to move around.
How to calculate for settings
When performing your calculations, remember that the formula to determine the circumference of a circle is C = d x π (pi, 3.14159) times the diameter. To calculate the number of settings for long tables, multiply the length of the table times two, divide the total by 75 cm (30 inches) and add two settings for the ends.
The number of settings for round tables
Using the above formula for finding the circumference of a circle, you can determine that a round table with a diameter of 120 cm (48 inches) can comfortably seat four or five people; a 135-cm (54-inch) table, six people; a 150-cm (60-inch) table, six people; and a 180-cm (72-inch) table, eight people. You wouldn't want a round table any larger than 180 cm (6 feet) because it would be too big for conversations to occur and there would be all that dead space in the middle.
Calculate the settings for long tables
When you use the formula for the number of settings per long table, you come up with the following results: A 1-metre by 1.8-metre (40 x 72-inch) table comfortably seats six guests; a 1.1- by 2.1-metre (44 x 84-inch) table, eight guests; a 1.2- by 2.4-metre (48 x 96-inch) table, either eight or ten guests if you squeeze in two at each end. Given the average size of dining rooms in today's homes, any table bigger than this would make getting into their seats impossible for guests.
Advantages of a round table
Besides your personal taste and feeling that a round table is more inviting and more conducive to socialising, there are practical matters. For one thing, round tables are space savers. For another, you don't feel so cheek-to-jowl with your fellow diners, and manoeuvring in and out of your seat is easier.
The advantages of the long table
On the other hand, a long table seems more formal but can be informal if you're serving family style. If you opt for a long table, make certain that the width is in proportion with the length and can accommodate serving dishes and centrepieces. In social terms, people find conversing with the people on either side of them and across from the table more comfortable.