I am trying to figure out how many yards of concrete are in a 17,000 square foot concrete slab

How thick is the slab?

Take your 17,000 sq-ft and multiply that by the thickness of the slab in inches divided by 12.

If you have a 4" thick slab, then you have 5666.67 cubic feet of concrete in your slab.

Now take the cubic feet of concrete and divide by the number of cubic feet in a cubic yard, which is 3'x3'x3' or 27 cu ft.

That 5666.67 cubic feet of concrete is equal to ~210 cubic yards of concrete.

You can use the online concrete calculator at this link.

How thick is the slab?
I believe 4" thick would be 210 yards


EDIT: I was too slow on the submit button... lol

Old rule of thumb.
4" slab= Divide sq. footage by 75.
6" slab= Divide sq. footage by 50.
This will give you the cubic yards needed.
17,000 sq. ft. would be 226.66 yards at 4", 340 yards at 6".
(The actual numbers are 81 sf. at 4", and 54 sf at 6", but the above numbers allow for waste factors.)

The slab is going to be for a house foundation, so I guess it is going to be a 6" slab with 21" by 21" footings.

Uh, you are pouring a slab - as a foundation - for a 17,000 square foot house?

SO, can we also assume, when you are tired of guessing, you'll get someone that knows what they are doing?

Hey its the funny sarcasm guy, I bet you laugh at your own jokes. Well, am I right?

David
You need to understand that you asked a vague question, then expected a concise answer! Give us a break, you want info try to include whats going on. Including the area/CLIMATE where you are planning to build.

Considering the size, either 17,000(unlikely) or 1700, its large enough to have a concrete contractor do it. Neither size is a DIY.

And I don't assume anything, which is why I don't answer a lot of questions because of the open ended approach.

Oops, I must have added to many zeros what I meant to say was a 1700 sq f slab for a house. How many yards of concrete would this size slab consist of?

It's about 21 yards, but that's only considering the 4 inches of slab - to that you would have to add the thickness of footings and grade beams to get a true number. If you visit the online concrete calculator you can plug all that information in and see all the variables.

Don't sweat the sarcasm - there are lots of truly helpful people here.

David,

Save yourself the trouble and just use the on-line calculator. That way you can get an answer for 4", 6" 1700sq ft and 17000 sq ft.

I can't belive someone wasted their time building a calculator for that. If you can't determine how much concrete your job requires, you have no business ordering it.

The questions already been answered, I don't need your sarcasm.  

I'm sorry, my comment wasn't directed at you. It was my observation, directed more at the person building the actual calculator. I really didn't intend you to take the way you did, but after reading my post I can understand where you are coming from.

But you know MDiver, when you're calculating costs and making budgets, it helps to know how much concrete you need even if you're not the one doing the ordering. When I asked my concrete contractor how many yards he was going to charge me for, I was confidant with his answer because I had come up with the same number on my own (by using the online calculator).

I don't let my guys use a slide rule or online calculator. Because if you understand the the calculation you don't ever have to ask again or use a tool. I always get as accurate as possible, at $100yd I don't waste concrete.

Dave - Please don't take offence (or anyone else for that matter) but this is a little math on one way to perform the calculation manually:

Nice work on the math - i like the dimensional analysis: See Wes above as i think this is the way to go for most folks.

12" Slab or Walls: 3x3x3 = 27 so 12" slab or walls are Sqft /27 --- therefore 6" walls or slab will go twice as far or: Sqft/54

Just remember 3x3x3 to get to your 12" of concretes then

12" magic number is 27
10" magic number is 32
8" is 41
6" is 54
and 4" is 81 (notice it is of course 2x the 8").

THerefore for 4" of concrete , 1700 sqft/81 = 21
if it's really 17,000 as above the 17000/81 = 210.