Because of our wide variety of pieces in the Arkahdia Arts line, we get this question every day.
Even though there are so many pedestals once you know the right underlying information,
whether it is a 24by36in oval glass coffee table or an 9x4 foot retangular granite conference table,
answering this question is a snap!
If you are not going to modify the bases by adhering it to the top and floor or adding a metal support pipe, then for table tops with separate bases there are only two things to concerned about when supporting the top when choosing the base.

SUPPORTING THE WEIGHT & PREVENTING TIPPAGE

Now for the details on each:

SUPPORTING THE WEIGHT

To support enough weight on a table does not mean only being able to hold up the table top. But also to support the things being put on the table top. Which in most cases are heavier than the top itself. (just think of the weight of a thanksgiving feast)

When calculating weight support take the total weight supportable by each base being used and add them together and then divide by four. This gives you the maximum weight of the top you will be able to support.

Let's try an example: Say you have a 200lb granite slab you would love to use as a table top. And you would love to use four simple ionic 30 inch columns each rated for 250 lbs. Would the 4 bases suffice?

OK... time for some simple math.... 4 bases * 250 lbs = 1000 lbs 1000 lbs / 4 = 250lbs supportable top

Since the table top weighs 200 lbs this setup can safely handle it.

PREVENTING TIPPAGE

Everyone has sat at a table with a missing leg, push down and your a first person witness to a mess... That's the "SEE SAW AFFECT"!

In addition you may see a table with a single base which was not wide enough, leaned on one end only to find the other end going up and your end going down.
That's the "SEE SAW AFFECT"!

In scientific terms this is know as the "The fulcrum affect" it's when your base with top act like a see saw!
The thinner the base gets in relation to the width of top the more the effect comes into play.

This is a direct affect of position of the bases and the diameter of the support in relation to the top.

The problems seem to arise when the size of the centered table base needs to support a distance greater than itself on the table top. This simply means if the width of the table base (or diameter if round) is less than 1/3 the length it is supporting it will be prone to tip.

Here are some simple examples.

W stands for WIDTH
C stands for DIAMETER
D must always be less than W or C to prevent tippage!

So the rule to prevent tipping is that the total length of the bases centered can not be less then the total length of top.

This rule applies to both the width and length (as illustrated in the next image)