# TABLE TOP SIZE vs BASE



## Tony B (Jul 30, 2008)

I thought I posted this earlier today when on my volunteer job. Apparently it didn't go through

Ok, When designing a table, whether dining or coffee, we have to consider the balance of the table. I have designed and built hundreds of tables without giving it a thought. i just went along with what looks right and never had a problem. While on my volunteer job today, I was looking at some tables on the internet. Some of them looked way too tippy for me and so the question arises.............
Is there some generic rule of thumb in determining the size of the base compared to the size of the top at a given height?
F'rinstance, I want a 30" X 60" top on a dining table with a 30" high pedestal base. What would be the minimum base size?
I know that center of gravity, height, weights of top and base all come into consideration. But if you are not a math major, is there a simple formula that can be applied to determine the size of the base?
We do know that if the base is the same size as the top, it will not tip. So how much smaller can I go without adding steel plates into the base?

I'm just looking for a simple 'rule of thumb' ratio if one does exist.

Thanks in advance.


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## Steve Neul (Sep 2, 2011)

I don't know if there is a rule. It's more of a common sense thing. You could have a smaller base on a table base if it were heavier than the top. It's like the round oak tables. The top might be around 45" in diameter but the base is only about 30" across. What makes it work is the bases are usually very heavy with about a 10" diameter center with massive legs. As far as your 30"x60" table that is pretty narrow for a dining room table, they are normally around 42" wide. For a narrow table like that I would make where the legs touch the floor nearly as wide as the table. The wider the table the more overhang you could use.


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## Tony B (Jul 30, 2008)

I just use the 30 x 60 as an example using a single pedestal leg with base.


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## FrankC (Aug 24, 2012)

I have always made the base 1/2 the width of the top on pedestal style tables, the bases can be much narrower than what you would think.


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## Toolman50 (Mar 22, 2015)

The Duncan Phyfe style of pedestal was almost as wide as the short side of the table. 
If your short side is 30” wide and you used Frank’s formula above, you would have 15” which in my opinion is way too short and would make the table tipsy. I would make it much wider to give a solid platform.


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## Chris Curl (Jan 1, 2013)

I saw a Woodwright's shop episode where Roy showed how to tell the tipping point of an object with legs without using math. You put a plumb line where the center of gravity is. In the case of a table with light legs, that would be a little below the top of the table. The heavier the legs, the lower the center of gravity. Then tip the table slowly. When the plumb passes the leg, then the table will fall. That works for chairs too.


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## woodnthings (Jan 24, 2009)

*Overkill is best!*

It's not only the center of mass of the table, when is the last time you leaned on the edge to assist in getting out of your chair? Older people will be doing more of this than young folks .... DAMHIKT:|


No matter how short or long the legs, they will always be underfoot. When you find that the leg is in your way, you either straddle it or rest your foot on it. Better safe (longer) than sorry (too short). :vs_cool:


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## GeorgeC (Jul 30, 2008)

Consider this statement carefully,
"It's not only the center of mass of the table, when is the last time you leaned on the edge to assist in getting out of your chair? Older people will be doing more of this than young folks .... DAMHIKT:|"


It is very important!!!


George


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## dbnewton (Feb 10, 2019)

You could make a rule of thumb fairly easily. Assume a 250 lb person (sort of a worst case) lifting themselves by the edge of the table. If the table weighs 25 lbs than to balance the forces the base would need to be 90% of the distance to the table edge. That would of course only just balance the forces and thus better to be conservative and use 95%.

Heavier table (especially if the table weight is down low in the pedestal as Steve pointed out above) could be narrower (analysis ignores where the center of mass is vertically for simplicity). But based on this the simplistic analysis the rule would be:

base width = top width * (1 - table weight/ 500 Lbs)

That is reasonably conservative, but don't invite the gravitationally challenged people to dinner to be safe.


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## FrankC (Aug 24, 2012)

This refers to pedestal based tables:

Did a bit of research, recommendation I found is base should be 6" - 12" narrower than top on each side, unfortunately this was a couple days ago and I did not bookmark the page, but that info is out there.

Just measured our double pedestal dining table, top is 42" base is 21 inches, have had people from babies to 90 years old sitting at it for last 25 years and it has never tipped. A simple search of pedestal tables will show many with bases much shorter than the tops. Why over build something just because you think something may happen despite what is commonly done and have to deal with a nuisance for the next how many years.

This is an example of a manufactured table with three legs with even more of a chance to tip:


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## woodnthings (Jan 24, 2009)

*A round 3 legged table has several tipping points ...*

If you apply downward pressure directly over one of the feet/legs attempting to tip it over, it will resist much more than the same amount of pressure applied centered between two of the feet. The pivot point changes as you apply force in different places around the rim and the amount of force changes as well because the leverage or moment arm changes. Three legged "anythings" resist lots of direct vertical force, but once the force is applied at an angle other than vertical, bad things happen sooner. :vs_cool:


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## terryh (Nov 11, 2013)

Most of the replies are correct as are the guidelines suggested. If you want to actually try to quantify things, the argument goes as follows for a table like that shown in the diagram. Imagine someone presses down on the outer edge of the table with a downward force F. The centre of gravity is marked c.g. and the total weight of the table is W. When the table is just on the verge of tipping (counter-clockwise) then the entire reaction from the floor will be the force R at point A. With the table in equilibrium (remember it is just on the verge of tipping), the sum of the moments of all forces about any point must be zero. If we choose to sum about point A, and arbitrarily choose a counter-clockwise moment as positive then we get

Fa - Wb = 0 

or F = Wb/a. If F > Wb/a, the table tips, if F< Wb/a it doesn't tip.

Rearranging, to solve for the distance a, gives 

a = Wb/F.

Obviously there is no simple one line answer, since it all depends on how hard someone pushes (force F), the weight of the table W, and the two dimensions a and b.


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## phaelax (Dec 24, 2018)

When I started building my pedestal table, I searched a lot online for some kind of standard proportion. The general consensus was, there is none.

But I would think that the weight and center of gravity of the base would play a part in how far out the base should spread. And I think terrry's post above points that out as well.


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## Tony B (Jul 30, 2008)

Terry's Post No 12 says it all. But without doing the math, I just scaled out a table on some graph paper. What looks good to me is that the base should be around 70-80% as large as the top if no significant amount of weight is added to the base. This is always how I have done it before and never had a problem. 
Hopefully, someone here feels like designing a simple pedestal table and actually doing the calculations.


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## woodnthings (Jan 24, 2009)

*Chances are ......*

Most likely the top will weigh more than the base which will increase the tipping factor.... "top heavy", as they say. If that's so, the "tipping factor" will be the distance in from the edge, of a straight line across the tips of the legs. This is where the the table will pivot like on a hinge and tend to tip when weight is applied on the edge. When weight is applied directly over top of a leg it will have less tipping effect. The diagram of forces does not take that into consideration, and it's important because it is a shorter length than the leg. A 3 legged table will be worse than a 4 legged one. JMHO 


This is a 3 dimensional problem, so you can't solve it in 2 dimensions.
:vs_cool:


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## Tony B (Jul 30, 2008)

I understand what u are saying about the pivoting point of rotation being less on a 3 legged table. I was thinking more of a round base for a round table and a rectangular base for a rectangular table. A rectangular base would also have to overcome aesthetic challenges as well as abrasion challenges from shoes. 
OR................pour concrete or lead in the base, LOL, which in itself would create additional challenges. I have never made a rectangular table with a single pedestal base before.


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## RefinedElements (Oct 20, 2013)

At Refined Elements and the Texas Urban Sawmill, we produce more live edge dining and natural edge conference tables than anyone in Texas. So we must be doing something right! I will say that we've never had any issues with tipping, etc. 

You could get overly complicated & work the match. Whip out the old physics book from college. I am an engineer and geek out over some stuff. But this is overkill. I agree with another poster, use your common sense. 

We do a lot of modern contemporary bases. I believe that narrower bases offer huge benefits when it comes to the ergonomic or industrial design of a table. We take human factors into very careful consideration when designing our piece for clients. 

Our standard bookmatch table tops which are 42-44 inches wide, usually mount a 24" - 25" wide base. This creates a LOT of extra leg room. Most don't consider seating as we do. We want people to relax and stretch their legs with minimum interference. We very, very rarely EVER go over 28". So 28" would be my safe suggestion on a 44" wide table (use this as a ratio). 

When doing my research years and years ago, most traditional makers produce very wide bases. 32-36" seems to be very common. I feel this is overkill unless you want to see more of the base or your are trying to match a more traditional look. 

The other thing that needs to be an important factor is the weight or mass of the table. We build very heavy tops and very heavy bases. I've even designed 20" wide pedestal bases for 44-48" tops. How? Well, we used 1.5" thick solid steel as the pedestal base. So these bases are heavy with a very low center of gravity.

I attached one such base. Like I said, we specialize in modern contemporary live edge so most our bases are either steel, stainless, bronze, nickel or cast iron. This means we can leverage the weight our of bases to the advantage of diners!


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## Tony B (Jul 30, 2008)

So lets see, if I want to build rectangular tables with small bases, I must buy metal working and welding equipment, a few cranes and forklifts, very large trucks, electrostatic paint equipment with accompanying sand blasting equipment, large warehouses, etc. Ok, what am I forgetting? Oh yeah, i forgot to give up the idea of rectangular tables with super heavy bases. Done! Now back to 4 legged tables...................much easier.


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## Steve Neul (Sep 2, 2011)

Tony B said:


> So lets see, if I want to build rectangular tables with small bases, I must buy metal working and welding equipment, a few cranes and forklifts, very large trucks, electrostatic paint equipment with accompanying sand blasting equipment, large warehouses, etc. Ok, what am I forgetting? Oh yeah, i forgot to give up the idea of rectangular tables with super heavy bases. Done! Now back to 4 legged tables...................much easier.


You could always hang guide wires from the ceiling and use a lightweight base. :vs_laugh:


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## woodnthings (Jan 24, 2009)

*Why not just .....*



Tony B said:


> So lets see, if I want to build rectangular tables with small bases, I must buy metal working and welding equipment, a few cranes and forklifts, very large trucks, electrostatic paint equipment with accompanying sand blasting equipment, large warehouses, etc. Ok, what am I forgetting? Oh yeah, i forgot to give up the idea of rectangular tables with super heavy bases. Done! Now back to 4 legged tables...................much easier.



Once you locate where the table will be, just dig down about 36" make a hole about 18" in diameter and set in some rebar. Pour your concrete around a sonotube with a metal plate on top with bolt holes to secure the table top. It's not easy to move around, but that's the whole idea...... just sayin' :vs_cool:


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## Steve Neul (Sep 2, 2011)

Weight in the base is very helpful however the problem with a rectangular table and a round base is there would be just too much overhang. When I build a table I make the assumption that sometime someone will attempt to sit on the table. Even if a table had a 1000lb base if the ratio to top versa the size of the footing it could still turn over if someone added their weight to the edge.


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## RefinedElements (Oct 20, 2013)

Tony B said:


> So lets see, if I want to build rectangular tables with small bases, I must buy metal working and welding equipment, a few cranes and forklifts, very large trucks, electrostatic paint equipment with accompanying sand blasting equipment, large warehouses, etc. Ok, what am I forgetting? Oh yeah, i forgot to give up the idea of rectangular tables with super heavy bases. Done! Now back to 4 legged tables...................much easier.


You joker! Actually, you do not need all that equipment. But my point wasn't metal. It was about the widths. You can go less wide than most people are doing IF you desire to have the gained leg room. You missed the point a bit but I might have been overly focused on talking metal. We've easily done solid wood bases at 26"-28" wide for 44-48". 30" wide would be a VERY safe bet. Hope that helps to a degree.


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## FrankC (Aug 24, 2012)

RefinedElements said:


> You joker! Actually, you do not need all that equipment. But my point wasn't metal. It was about the widths. You can go less wide than most people are doing IF you desire to have the gained leg room. You missed the point a bit but I might have been overly focused on talking metal. We've easily done solid wood bases at 26"-28" wide for 44-48". 30" wide would be a VERY safe bet. Hope that helps to a degree.


Probably not, I think some here have their minds made up despite any evidence to the contrary.


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## Tony B (Jul 30, 2008)

RefinedElements said:


> You joker! Actually, you do not need all that equipment. But my point wasn't metal. It was about the widths. ................


Yup, my Yankee humor at work. LOL
Anyway, I am currently living and traveling in my RV and you can tell when I get bored. I get on here.Anyway, being away from real furniture tends to make me think in the abstract and forget that real furniture has weight even on the the top, which adds to the CG and so, I now remember that the weight of the top helps steady things also. 

..........but, I still like the idea of all that equipment. 

Tony B


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