What is the ratio of the diameter of a table top to the width of the base?

This involves several factors, size of table, intended use, design, there are "GENERAL" formula's out there, for certain designs. It comes down to intended use and its stability. Example: In bowl turning, the general formula is 2/3 bowl area, 1/3 base area, this is for beauty an balance to the eye, that said, I have also seen bowls that shatter that formula and are still beautiful an pleasing. My suggestion is go to a furniture store and find a table that you like that is similar, then take some measurements. Good-Luck