Is this a dining table? You'll need larger than that. Typically about 2' larger than the table so your chairs will sit fully and comfortably on the rug when pulled out.

I would get a 5' or 6' rug :) I think that it looks a lot better to have excess.

An 8' diameter round rug works best for a 48" round table.

Rug should be 36-42" larger than the table top all around yet not run into baseboards or furniture against the walls. Measure 36 and 42 inches away from your table top and tape the 4 points of the compass on the floor with painters tape. Measure across from north to south and then from east to west for the size to tell the tale. Go larger if that isn't a standard rug size. If it will run into walls or furniture, you may have to go a bit skimpy. Chairs need scoot & sit space without falling off the rug.