How many yards of concrete do I need for a 20×40 slab | how much concrete do I need for a 20×40 slab | how many cubic feet of concrete do I need for a 20×40 slab | How many yards of concrete do I need for a 20×40 slab at 4″ thick | How many yards of concrete do I need for a 20×40 slab at 5″ thick | How many yards of concrete do I need for a 20×40 slab at 6″ thick.

Weight of Ready mix concrete in dry condition is about 133 lbs per cubic foot, 3600 lbs per cubic yard, or approximately equal as 2136 kg per cubic meter. The weight of concrete is determined by its density, which can vary based on the amount of aggregate, water, and air in the mix.

In United States, based on Imperial and US customary measurement system, 1 cubic yard is unit of measurement of volume represented by 3 feet long by 3 feet wide by 3 feet depth (3’×3’×3′ = 27 cubic feet), so 1 cubic yard is equal to 27 cubic feet.

You need to calculate the volume of concrete in cubic yard or in cubic feet or in cubic meter or in rmc truck before ordering the mixed concrete. Volume is calculated by multiplying length, width and depth of slab. Here you have given a slab of 20 feet in length and 40 feet in wide at 4 inches thick, it’s depend on, is this a slab on the ground or it is elevated, rules differ for both, since failure of ground slab would not kill anyone whereas failure of an elevated slab could.

Thumb rules involves the safety factor that deciding the thickness of slab, 4 inch thick is generally for ground slab, heavy traffic and heavy load, you should take depth 5 or 6 inch thick and for an elevated slab generally thickness should be 5″ to 6″, and 4 inch thick is also made to use in normal conditions.

Generally standard thickness of slab is 4 inch thick in normal conditions, if slab have heavy traffic and heavy load, you should take depth 5 or 6 inch thick. In this article we have to calculate required quantity of concrete in cubic yard & in cubic feet and cubic meter for a 20×40 (800 sq ft) slab at 4 inch, 5 inch or 6 inch thick.

For small project you can purchase the concrete bag which are available in different bag size and weight condition such as 40lb, 60lb bag, 80lb bag, 90lb bag and etc and for large project you may ordering the contractors for ready mix concrete in cubic yard, they can supply it in truck commonly known as rmc or dump truck. there are several sizes of RMC truck on road, most common concrete truck has drum capacity of 11 to 15 cubic yards, however due to weight limit on the road they can carry 8 to 11 cubic yard of concrete. Most common is 8 & 10 cubic yards, for road Project small lots of concrete need to be transferred to various location so small truck may hold 5 cubic yards.

**How many yards of concrete do I need for a 20×40 slab**

To determine the how much concrete do I need for a 20×40 slab, you can solve in following steps:-

Step 1 :- calculate the volume in cubic feet:- you have given 20×40 slab (length × width), consider it is 4 inch thick, 4 inch = 0.33 feet, to determine the volume of slab, you need to multiply all dimensions, such that = 20′×40′× 0.33′ = 264 cubic feet, at 5 inch thick, volume of slab is 20′×40′× 0.416 = 332 cubic feet and at 6 inch thick, volume of slab is 20′×40′× 0.5 = 400 cubic feet.

Step 2 :- converting cubic feet into cubic yard:- now converting into cubic yard, you should divide it by 27, so volume of concrete you needed for 20×40 slab at 4 inch thick in cubic yard = 264/27 = 10 cubic yards, at 5 inch thick = 332/27 = 12.5 cubic yards & at at 6 inch thick = 400/27 = around 15 cubic yards.

Step 3:- add 10% extra which would be wastage during mixing and pouring.

Regarding this, “how many yards of concrete do I need for a 20×40 slab?”, at 4 inches thick, generally you will need approximately 10 yard or 264 cubic feet of ready mix concrete for a 20×40 slab, at 5 inches thick slab 12.5 yards or 332 cubic feet of readymix concrete are required, while at 6 inches thick slab approximately 15 yards or 400 cubic feet of readymixed concrete is necessary.

**How much concrete do I need for a 20×40 slab**

Regarding this, “how much concrete do I need for a 20×40 slab?”, at 4 inches thick, generally you will need approximately 10 yard or 264 cubic feet of ready mix concrete for a 20×40 slab, at 5 inches thick slab 12.5 yards or 332 cubic feet of readymix concrete are required, while at 6 inches thick slab approximately 15 yards or 400 cubic feet of readymixed concrete is necessary.

**How much concrete do I need for a 20×40 slab at 4″ thick**

Regarding this, “how much concrete do I need for a 20×40 slab at 4″ thick?”, at 4 inches thick, generally you will need approximately 10 yard or 264 cubic feet of ready mix concrete for a 20×40 slab. Mathematical calculation:- 1) first calculate the volume in cubic feet by multiplying all dimension such that = 20′×40′× 4″ = 20′×40′× 0.33′ = 264 cubic feet, 2) to determine the volume of slab in cubic yards, you should divide it by 27, so volume of concrete you needed for 20×40 slab at 4 inch thick in cubic yard = 264/27 = 10 cubic yards.

**How much concrete do I need for a 20×40 slab at 5″ thick**

Regarding this, “how much concrete do I need for a 20×40 slab at 5″ thick?”, at 5 inches thick, generally you will need approximately 12.5 yard or 332 cubic feet of ready mix concrete for a 20×40 slab. Mathematical calculation:- 1) first calculate the volume in cubic feet by multiplying all dimension such that = 20′×40′× 5″ = 20′×40′× 0.416′ = 332 cubic feet, 2) to determine the volume of slab in cubic yards, you should divide it by 27, so volume of concrete you needed for 20×40 slab at 5 inch thick in cubic yard = 332/27 = 12.5 cubic yards.

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**How much concrete do I need for a 20×40 slab at 6″ thick**

Regarding this, “how much concrete do I need for a 20×40 slab at 6″ thick?”, at 6 inches thick, generally you will need approximately 15 yard or 400 cubic feet of ready mix concrete for a 20×40 slab. Mathematical calculation:- 1) first calculate the volume in cubic feet by multiplying all dimension such that = 20′×40′× 6″ = 20′×40′× 0.5′ = 400 cubic feet, 2) to determine the volume of slab in cubic yards, you should divide it by 27, so volume of concrete you needed for 20×40 slab at 6 inch thick in cubic yard = 400/27 = 15 cubic yards.