Choosing the restaurant table base to use with your table top should be taken seriously as it can cause you nightmares if not done correctly. If you choose too small of a base, the table can be tippy and spill drinks or even worse injure someone. If you choose a base that is too large, it could make it difficult for the customer to sit comfortably, or even worse the legs can stick out and trip someone. There is a difference in base sizes used for standard table height and Bar Height. Basically, you would use 1 size bigger table base under a bar height table top, but I will note more information on that below. I will address the round bases in my next article.
Some of the more common sizes of Cross Table Bases are the 22x22, 30x30, 22x30, 36x36 and a 22x5 "T" Base. The cross bases look like an "X" sitting on the floor, the specialized 22X5 "T" base looks like an upside down "T" that has 2 legs across from each other.
The 22x22 base will work for a 24x24 restaurant table top to a 30x30 top (also 24" to 30" Round, ), that would mean that the base is 2" under the top which is a little awkward for the customer, but there is no base smaller. You can rotate the base so that the legs will point directly at the customer so the chairs can be pushed in. The 30x30 top will have 8" from the end of the base to the side of the top, so there is plenty of space.
The 30x30 table base will work for a 36" X 36" to a 42" X 42" (also 36" to 42" Round). That will give 6" - 12" of clearance from the legs to the side of the table. It should not be used with anything larger or it will be tippy. If you want to make your 42x42 more sturdy, go up 1 size as the legs will not stick out.
The 22x30 table base will work for rectangular tops from a 24" X 42" to a 30" X 48". It will work for anything in between, but I would not put anything longer than 48" or wider than 30" on it. If you have tables larger than this, you would want to use the 22x5 "T" base.
The 36" X 36" table base will work for a 42" X 42" to a 48" X 48" (also 42" to 60" Round). That will give 6" – 12" of clearance from the legs to the side of the table. You can can use smaller bases under round tops as there is no corners that stick out for people to lean on and tip the table.
The 22x5 "T" base will cover most other tops. It is made for rectangular table top larger than 30" X 48", however, it should not be used on anything wider than 36". Sometimes, you may even need a third one in the center of the table if it is very long or your table could warp. This base can even be set up with 3 to 4 of them under a very large round table top, you would want to test the stability though.
For Bar Height Table Bases, as I noted above, you will basically want to go up 1 size of base. The only problem with doing this is that the base legs will come right out to the edge of the table top in some cases. An example is that if you have a 30x30 or 30 round table top, depending on the crowd that you get, the 22x22 will work as long as people are not leaning hard on the top, but the 30x30 base will be a lot more stable, but the legs will be right to the edge of the top. You have to make the decision yourself on which way you want to go with this. Another example is that you can use a 36x36 base under a 48x48 top for standard height, but you would not want to do this at bar height as that would be tippy. That is a case where you would want to use multiple 5x22 "T" bases. The "T" bases are very handy for bar height tables that do not fit in the pattern of sizes.
The choice of what base to use can be a difficult decision in some cases, but others are simple. Make sure to do your research as to what size of base that you want. If you do not have any experience in this, sneak a tape measure into a restaurant and measure their tops and bases and make the decision for yourself if the top is too tippy or the legs stick out too far.