The rule with dinings areas is that there should be enough rug all around the table so that when the chairs are pulled out they are still on the rug. You don’t want you dinner guests to feel like they are falling of the rug!
You need to allow 70-80cm all the way around the table, so if you add 140-160cm to the length and width of your table and you will have your rug size.
Rugs are also fantastic for acoustics in a busy dining room and will help to absorb the noise.
Table 150 x 150cm
Table 120 x 220cm