How do i calculate a 4" concrete pad

Question

if i have a concrete pad that is 13' x 13' x 4' , how do i figure out the amount of concrete i need by useing a calculator. I understand how to use cubic feet but what do i do with the extra inches? how to do convert those? please help! thanks!!

Answer 1

13 x 13 = 169 feet

(1 foot / 12 inches) x 4 = .333

169 feet x .333 = 56.277 cubic feet

56.277 cubic feet / 27 cubic feet = 2.08 cubic yards.

Concrete is sold by the cubic yard.  

Be sure to tell the mix company what you are going to use the pad for, so they can make sure you get the right mix, with the right amount of aggregate.  You did not mention using any re-enforcement wire or re-bar.  

Answer 2

4" is 1/3 of a foot.

Concrete is ordered by the cubic yard in any event.

(13 x 13 x 1/3) / 27 = 2.1 Cu Yd.s

Answer 3

any extra inches should be converted to decimals and used that way...4 in. =.33  5 in. = .42  6 in. = .5 etc...length x width x thickness equals cu. ft.   divided by 27 gives you cu.yds...

Answer 4

13' times 13' give you the area.  To get the volume multiply the result in the first computation by what portion 4 inches is of a foot.  (hint--it's .33333')  That gives you the number of cubic feet in your pad.

Answer 5

I would say less than three yards, but many cement trucks will deliver minimum loads only.  Perhaps they only will deliver a minimum of 4 yards, or five yard on their truck out to you.  Inquire several concrete suppliers, they will do the math for you. And you can work out the best price for yourself.

If you are self mixing with bag crete, let the supplier do the math for you as well.  Good luck on the self mixing, all the dust gets to me and makes my bowls turn concrete hard.  uuuggg.