Formulas for figuring how tall a cabinet will be at its longest point. March 14, 2004

Question

What is the formula for calculating the tallest cabinet that you can stand up in a room?

Forum Responses

(Cabinetmaking Forum)*From contributor S:*

You measure from long point to long point, or the longest diagonals. A cabinet 24" deep by 84" tall would be approximately 87 3/8" from longest points.

*From contributor K:*

If you need to go all the way to the ceiling, build the toe kick separate and set the cabinet on top.

*From contributor D:*

I believe that if you are looking for the formula, you will have to find the square root of ((Height X height)+(Width X width)). For example, a cabinet that is 24 inches deep and 94 inches tall, you would work like this:

94 x 94 = 8836

24 x 24 = 576

then add 8836

+576

=9412

Then hit that magic sqrt button on your calculator and you will need a ceiling height of 97.0125 inches to stand that cabinet up. Also, you can look on your framing square and it is the same formula as the 6 & 8 = 10 triangle (a squared)+(b squared)=(c squared)

*From contributor B:*

24" deep tall cabinet height = ceiling height - 4". Leaves a small gap easily covered with 8010 crown. No calculator... Has worked for me for years.

*From contributor M:*

It's the Pythagorean Theorem.

A Squared + B Squared = C Squared

*From contributor M:*

I'm asking a few people this question
If you have a designated room height and you know the depth or width of a cabinet, how do you figure out the tallest cabinet you can make to fit in that room?

You need to know either the depth or width, plus the height of the room to figure it out. You won't be able to figure it out just by the Pythagorean Theorem for that instance.

If you know the height you want to make it you can take what your width or depth needs to be and figure out what the cross dimension would be by the Pythagorean Theorem.

*From contributor M:*

The point B will be at its highest point when it is directly vertical from B. That means that the height will be the distance from B to D. What is that? Pythagorean Theorem. You want that distance to be less than 107". So make the height something x so that x^2 + 26^2 < 107^2, or x < 103.793".

That is what I got in response to saying: If I have a room that is 107 high and a cabinet that is 26" deep, how do I figure out what the tallest cabinet I can put in this room will be?

*From the original questioner:*

Thanks for the responses. This is exactly what I was looking for.

*From contributor M:*

The funny thing is, I really don't understand what the ^ and the < mean and how to actually figure it out. I've always deducted my crown and base, then I knew what I had left to work with and adjusted accordingly. Anyone care to explain that mathematical equation?

*From contributor M:*

I must say, I do my best work at 3 am. After beating myself over the head to understand and figure it out, I finally got it. Here is exactly what you do step by step:

Let's say our room height is 107". We know we want this cabinet to be 26" deep or wide. Doesn't matter which.

Now we want to find out how tall we can make this cabinet without it hitting the ceiling. Based on the following formula, it will tell you what the tallest cabinet you can make is when the highest point is vertical.

Take 107x107= 11449

Take 26x26= 676

Subtract your room height of 11449 by the depth or width, which is 676, which will give you 10773. Now take 10773 and hit the Square Root button. That will give you a maximum cabinet height of 103.793 or 103-3/4" +

So your cabinet will be 26"x103-3/4+

PS - I'd recommend you make it a bit under that, since the client wouldn't want you to just scrape their ceiling.

*From contributor T:*

I guess we can agree that a 107" cabinet does not fit into a 107" space? If you want to get your cabinet tight up against the ceiling, you have to make a separate base and shim the cabinet on top of it tight against the ceiling. Trying to tilt a tall cabinet up in a room is crazy talk.

*From contributor M:*

Not crazy talk. What if you go into a house that only has ceilings that are 8ft? You have a base of 3" high and the cabinet is 28" deep because of the TV. How do you plan to stand it up anywhere in the house? You have to tip it down to get into the door way. Right? :)

*From contributor M:*

To add to my post you can do the simple formula of:

C^2-B^2=A^2

*From contributor T:*

Contributor B, yes, we got back to your clg. ht. minus 4" or 3" if you like to rub your shoes on the bottom. This is the correct way.

How about a 3/4" scribe to the floor? The customer and designer definitely sign off on that one.

By the way, it can be done.

*From contributor M:*

Contributor T, I don't know about you, but I sure as heck don't like making more work for myself than necessary. If you have a separate base or even a fixed base, shim where necessary and shoe mold if on wood or tile floors.

With the top, leave it short, add a header then attach your crown to that. The header would allow you to ride your crown up and down on.

*From contributor T:*

Yes, the difference can always be taken up by riding the crown, but that is not what was asked. The question was "How tall of a cabinet can I get into a room?"

It is not possible to get a tight fit at the ceiling by tilting up the cab. Your point of more work is well taken and agreed. I think the correct answer to the question is the Pythagorean Theorem less 2". This way the one piece cabinet will tilt up without hitting the ceiling and come to rest 2" below the ceiling. I believe this is as high as you should go in one piece.

I make nearly 90% built-ins and I would never try a one-piece cab to the ceiling. It can't be done. By the way, I don't use shoe mldg. I hate the stuff. Make a loose base and scribe it to the floor. It takes a little time but the job looks well done. No gaps, no fills, no errors.

*From contributor M:*

It's not possible to make every cabinet end up 2" from the ceiling, unless you put a separate base and stand it up on top. I'll agree with you on the separate base. It does take a bit more time, and does look nicer.

*From contributor T:*

When I said to shim, I meant to shim the cab on top of the base, not to shim the base. Either way, I would have a loose front on my base that gets scribed perfectly to the floor. It looks pro.

*From contributor L:*

When a customer insists on a one-piece cabinet, I show him the design wont work with a roll of masking tape, a tape measure, framing square and his plans. I ask how deep the top of the cabinet is (24). Stick the tape on the floor 24 and then ask him how tall the cabinet is (96). The tape is placed so it is at a right angle to the first piece and is 96. Next I hold the tape measure on the short leg and let the customer find where the tape crosses the long leg at 96 and he sees the problem with his one-piece cabinet design.

If I am at the customer's home, I get out a small ladder and do the same thing, but use two tape measures and use the ceiling and a wall.

*From contributor R:*

If it is a 28'' cabinet, I just pull down 28'' on my out feed table, hook my tape on it, pull across the table and mark the ceiling height, then measure the length of that. It has to be faster than the formula, as it only takes 10 seconds to complete.

*From contributor T:*

I'm not being facetious, but how do you get the 28" deep cab, which is as tall as the ceiling, in the room upright?