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I have an area 1200 feet long and 30 feet wide or 36,000sq ft i need to know how many yards of concrete to purchase, and what is the formula used to derive answer.

- black

You have to know how thick you want the concrete to determine the volume to order. Lets suppose you want it 4" thick.

This needs to be expressed as a fraction of a foot, 4"/12 in per foot = 1/3 = 0.3333...

Volume is area x thickness = 36000 sq ft x 1/3 ft = 12000 cu ft.

(BUt this depends on the thickness you want. There are 3 feet per yard, so in cubic measure 3x3x3 = 27 cu ft/cu yd

12000 cu ft / 27 cu ft/cu yd = 444.5 cu yd

This needs to be expressed as a fraction of a foot, 4"/12 in per foot = 1/3 = 0.3333...

Volume is area x thickness = 36000 sq ft x 1/3 ft = 12000 cu ft.

(BUt this depends on the thickness you want. There are 3 feet per yard, so in cubic measure 3x3x3 = 27 cu ft/cu yd

12000 cu ft / 27 cu ft/cu yd = 444.5 cu yd

- Guest

Anonymous wrote:You have to know how thick you want the concrete to determine the volume to order. Lets suppose you want it 4" thick.

This needs to be expressed as a fraction of a foot, 4"/12 in per foot = 1/3 = 0.3333...

Volume is area x thickness = 36000 sq ft x 1/3 ft = 12000 cu ft.

(BUt this depends on the thickness you want. There are 3 feet per yard, so in cubic measure 3x3x3 = 27 cu ft/cu yd

12000 cu ft / 27 cu ft/cu yd = 444.5 cu yd

JUST ROUND IT OFF..SAY 10X10X3.5 IS ABOUT A YARD..CLOSE ENOUGH

VERY EASY

- DANO

Got my house lot about 1500 sq.feet and i dont kow how much if it going to convert sq.meter.please help me to calculate it.

Vj

Vj

- vj

I have a area 9ft x 12ft x 3" thick how much concrete :?:

- Gary

how much concrete would i need to pour 52,272 sq yards 1'1/2 deep![/quote]

- Guest

vj wrote:Got my house lot about 1500 sq.feet and i dont kow how much if it going to convert sq.meter.please help me to calculate it.

Vj

1500 sq ft = how many yards

- Guest

vj wrote:Got my house lot about 1500 sq.feet and i dont kow how much if it going to convert sq.meter.please help me to calculate it.

Vj

- Guest

black wrote:I have an area 1200 feet long and 30 feet wide or 36,000sq ft i need to know how many yards of concrete to purchase, and what is the formula used to derive answer.

- Guest

[quote="Gary"]I have a area 9ft x 12ft x 3" thick how much concrete :?:[/quote]="Frank" I have a area 5ft. x9ft. x 4" thick, how much concert?[/list]

- Guest

Anonymous wrote:="Frank" I have a area 5ft. x9ft. x 4" thick, how much concert?[/list]Gary wrote:I have a area 9ft x 12ft x 3" thick how much concrete :?:

- Guest

black wrote:I have an area 1200 feet long and 30 feet wide or 36,000sq ft i need to know how many yards of concrete to purchase, and what is the formula used to derive answer.

- Guest

black wrote:I have an area 1200 feet long and 30 feet wide or 36,000sq ft i need to know how many yards of concrete to purchase, and what is the formula used to derive answer.

- Guest

Gary wrote:I have a area 9ft x 12ft x 3" thick how much concrete :?:

- Guest

Gary wrote:I have a area 3ft x 10ft x 6" thick how much concrete :?:

- Guest

vj wrote:Got my house lot about 1500 sq.feet and i dont kow how much if it going to convert sq.meter.please help me to calculate it.

Vj

- Guest

Tell me if I'm right...

I'm pouring a 9.5' X 7.4' X 3"

9.5*7.4*.25 = 17.575

17.575/27 = 0.65 yards, which equals to little less than a yard.... right?

Or, if I round off to make sure I have enough of cement I could:

10*8*.25 = 20

20/27=.74 yards

Now I need to know how may bags of ready mix concrete I need.

How many bags 40 lbs bags would I need for .74 yards?

How many bags 40 lbs bags would I need for .65 yards?

How many bags 80 lbs bags would I need for .74 yards?

How many bags 80 lbs bags would I need for .65 yards?

Two more questions: I was told that I must have 4" because of the way the ready mix settles. Is this true? I will be mixing this myself and I want to save money too!

What would happen if I only poured 3"?

I'm pouring a 9.5' X 7.4' X 3"

9.5*7.4*.25 = 17.575

17.575/27 = 0.65 yards, which equals to little less than a yard.... right?

Or, if I round off to make sure I have enough of cement I could:

10*8*.25 = 20

20/27=.74 yards

Now I need to know how may bags of ready mix concrete I need.

How many bags 40 lbs bags would I need for .74 yards?

How many bags 40 lbs bags would I need for .65 yards?

How many bags 80 lbs bags would I need for .74 yards?

How many bags 80 lbs bags would I need for .65 yards?

Two more questions: I was told that I must have 4" because of the way the ready mix settles. Is this true? I will be mixing this myself and I want to save money too!

What would happen if I only poured 3"?

- brianm1
**Posts:**1**Joined:**Wed Jul 12, 2006 5:42 am

Brian:

Your calculations are correct. And yes, always order a little more than you think you will need. The sub-base is never perfectly flat and more times than not, a little more is needed. Unless you order more . . . Murphyâ€™s Law!

The reason concrete is poured at a predetermined minimum thickness is due to load bearing and structural strength, not how it settles. Four inches (4") is stronger than three inches (3") of course and if itâ€™s anything but a small sidewalk, I suggest at least four inches.

If I remember correctly, an 80 pound bag of Sacrete (ready mix in a bag, just add water) makes 6/10ths of a cubic foot of concrete. Thatâ€™s 45 bags a cubic yard. At 0.75 yards, thatâ€™s 34 bags. If itâ€™s $3 a bag, thatâ€™s $102 not including tax . . . plus, you have to mix every bag!!! That takes time!!!

At four inches (4"), 0.87 yards * 45 = 40 bags

Save yourself aggravation and order a yard of concrete from a plant. There will be a short load charge but the cost should still be around $100 give or take. A quick call to the nearest plant and they will give you a price. The minimum strength I would pour would be 3000 psi mix (5 sack) but check city codes as many require stronger concrete.

FWIW, donâ€™t get the concrete too wet as itâ€™ll make the mix weaker. A good workable consistency is what you want.

If you're going to be walking on it after it's cured, don't get it too smooth or it'll be really slick when it gets wet. A light broom finish will make it safer for walking, especially if it's outside. When you get the concrete with the finish you want, cover it with plastic or a curing compound so the top doesn't dry too quick.

George

Your calculations are correct. And yes, always order a little more than you think you will need. The sub-base is never perfectly flat and more times than not, a little more is needed. Unless you order more . . . Murphyâ€™s Law!

The reason concrete is poured at a predetermined minimum thickness is due to load bearing and structural strength, not how it settles. Four inches (4") is stronger than three inches (3") of course and if itâ€™s anything but a small sidewalk, I suggest at least four inches.

If I remember correctly, an 80 pound bag of Sacrete (ready mix in a bag, just add water) makes 6/10ths of a cubic foot of concrete. Thatâ€™s 45 bags a cubic yard. At 0.75 yards, thatâ€™s 34 bags. If itâ€™s $3 a bag, thatâ€™s $102 not including tax . . . plus, you have to mix every bag!!! That takes time!!!

At four inches (4"), 0.87 yards * 45 = 40 bags

Save yourself aggravation and order a yard of concrete from a plant. There will be a short load charge but the cost should still be around $100 give or take. A quick call to the nearest plant and they will give you a price. The minimum strength I would pour would be 3000 psi mix (5 sack) but check city codes as many require stronger concrete.

FWIW, donâ€™t get the concrete too wet as itâ€™ll make the mix weaker. A good workable consistency is what you want.

If you're going to be walking on it after it's cured, don't get it too smooth or it'll be really slick when it gets wet. A light broom finish will make it safer for walking, especially if it's outside. When you get the concrete with the finish you want, cover it with plastic or a curing compound so the top doesn't dry too quick.

George

- Dirtman
- Expert
**Posts:**574**Joined:**Sat Jan 21, 2006 2:04 pm**Location:**California

- Guest

Gary wrote:I have a area 9ft x 12ft x 3" thick how much concrete :?:

- Guest

Anonymous wrote:

Vj

- Guest

- dlavender@adelphia.net

lenght x width x depth divided by 81 = number of yards of concrete needed

- Guest

lenght x width x depth divided by 81 = number of yards of concrete needed

Sorry but the formula you give is wrong.

This formula is similar to those found on some concrete calculators but . . . you donâ€™t use depth in the calculation and itâ€™s only for 4" thick concrete. The formula, provided that one chooses to use it, is length in feet * width in feet divided by 81. Again, this ONLY works for concrete that is 4" thick

A standard formula for calculating cubic yards is length (in feet) * width (in feet) * depth (in feet) divided by 27.

To convert inches to feet, divide inches by 12.

George

- Dirtman
- Expert
**Posts:**574**Joined:**Sat Jan 21, 2006 2:04 pm**Location:**California

- Dirtman
- Expert
**Posts:**574**Joined:**Sat Jan 21, 2006 2:04 pm**Location:**California

24 by 32 house with 8 inchwa;ll and a wall hight of 6feet with floor area of 4inchs dept

- max

my driveway is 20ft. long 8ft wide and 6 inches deep the cost to pave this the quote is $8.95 per cubic yard.

I convert the volume = 20x8x.5 = 80 sq. feet.

so how do I convert sq. feet to cubic yard?

I convert the volume = 20x8x.5 = 80 sq. feet.

so how do I convert sq. feet to cubic yard?

- bhardas

bhardas wrote:my driveway is 20ft. long 8ft wide and 6 inches deep the cost to pave this the quote is $8.95 per cubic yard.

I convert the volume = 20x8x.5 = 80 sq. feet.

so how do I convert sq. feet to cubic yard?

8 x 20 is square feet. You calculated cubic feet . . . 8 x 20 x 0.5 = cubic feet. Divide cubic feet by 27 for cy (cubic yards), so 80 / 27 = 2.97 cy. Round up to 3 cy.

However, 3 cy is assuming a perfect subgrade. As nothing is perfect, add 10% to take an inperfect subgrade into account. Ordering 3.3 cy is much cheaper than getting a truck with 3 cy, finding out you need a little more concrete and having to order an additional 0.3 cy . . . at a short load price (3 cy in most locations).

If you're really going to pour this driveway (assuming this isn't a homework problem), write back as $8.95 per cy is way too cheap! The cement alone costs more than that (at a discount price)!

George

- Dirtman
- Expert
**Posts:**574**Joined:**Sat Jan 21, 2006 2:04 pm**Location:**California

330 sq.feet

Vj

- Guest

34 posts
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