formula to figure concrete square yard needs

[tcb]

I lurked long before i posted and have learned much from the talent on this board so now i have a question. I thought i knew this but one supplier agrees with me and another is about two yards higher. garage pad to be poured is 20x35x.5 . i am coming up 9.7 yards or so, am i correct or wrong. oh and if there are any finishers on this board in alabama and they need something to do i will supply the BBQ. anyway all replies will be appreciated. i am doing all work myself and it has been awhile since i did finish work on crete so do not be afraid to throw out helpful hints and potential boo boos.

tim

 

[Birdman]

Here is a calculator.

 

[Dargo]

Awesome link! I'm working on finishing a rather long concrete driveway and that link had a lot of useful information such as how wide and how often expansion joints should be placed. Thanks!

 

[beenthere]

width x length x height

Are your measurements in feet? So the .5 is 6 inches?

Then 12.96 cu yd is what I get. (also the same with the calculator).

 

[bczoom]

I came up with 10.80 yards (if your .5 means 5" thick).

5/12*35*20/27

Tim,

Not sure what your base is like but somehow concrete "disappears". If you order 11 yards, you "might" have enough but as it compresses your base and stuff, 11 yards might not be enough. Personally, I'd probably order 12 yards then have a small project lined up if there's any spare.

Brian

 

[Egon]

</font><font color="blue" class="small">( width x length x height )</font>

Yard of concret equals 27 cubic feet

{ width[ft.] x length [ft.] x height [ft] } / 27 = cubic yards.

Egon

 

[HuskerInVA]

Google does these type of calculations.

got to google.com and enter:

20 ft x 35 ft x 6 inches in cubic yards

click search and...

(20 ft) x (35 ft) x (6 inches) = 12.962963 cubic yards

 

[imported_OWDouglas]

I'm getting 12.96cu yds with my constuction calculator. I also assumed that the .5 is 6 inches

 

[tcb]

thanks to all, it appears i and one supplier were wrong and the least expensive is right. 13 yards x 67.00 is going to hurt but not as bad as some i have read on here. thanks again.

tim

 

[Tom_H]

Assuming that your measurement units are all in feet (you didn't say) and that they are completely accurate, the correct calculation is 12.962962 cubic yards. This rounds to 13. Concrete can be made by many different formulas. Some mixes can shrink and some can expand as they cure. Assuming you are using a mix whose volume will remain constant, I would ask them to make it the smallest increment higher than 13 that they are willing to. 13 and a quarter is what I'd order if they'd do that.