To determine how many bags of concrete you need for an 8×16 slab, you’ll need to calculate the volume of concrete required. Here’s how you can do it:

1. Calculate the area of the slab:

Area = Length (8 feet) x Width (16 feet) = 128 square feet.

2. Determine the thickness of the slab. Typically, for a standard residential concrete slab, you might use a thickness of 4 inches (0.33 feet).

3. Calculate the volume of concrete required:

Volume = Area x Thickness = 128 sq. ft. x 0.33 ft. = 42.24 cubic feet.

4. Convert the volume to cubic yards. There are 27 cubic feet in 1 cubic yard, so:

42.24 cu. ft. / 27 = approximately 1.57 cubic yards.

5. Now, you can calculate how many bags of concrete you need. A standard 80-pound bag of concrete mix typically yields about 0.6 cubic feet of concrete. So: Number of bags = 42.24 cu. ft. / 0.6 cu. ft. per bag ≈ 70.4 bags.

Since you can’t buy a fraction of a bag, you would need approximately 71 bags of concrete to pour an 8×16 slab with a 4-inch thickness. It’s a good idea to buy a couple of extra bags for any adjustments or potential waste.

A bag of concrete ready mix made of blended mix of Portland cement, sand gravel and other approved ingredient or admixture, generally, dry ready mix concrete are available in different bag size and weight condition such as 40lb, 60lb bag, 80lb bag, 90lb bag and etc.

Regardless of size 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 8 feet in length and 16 feet in wide, what is thickness of slab?, 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 8×16 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 8×16 (128 sq ft) slab at 4 inch, 5 inch or 6 inch 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.

**How many bags of concrete do I need for a 8×16 slab**

To determine the how much concrete do I need for a 8×16 slab & how many bags of concrete do I need for this, you can solve in following steps:-

Step 1 :- calculate the volume in cubic feet:- you have given 8×16 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 = 8′×16′× 0.33′ = 42.24 cubic foot, at 5 inch thick, volume of slab is 8′×16′× 0.416 = 53.25 cubic foot and at 6 inch thick, volume of slab is 8′×16′× 0.5 = 64 cubic foot.

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 8×16 slab at 4 inch thick in cubic yard = 42.24/27 = 1.56 cubic yards, at 5 inch thick = 53.25/27 = 1.97 cubic yards & at at 6 inch thick = 64/27 = 2.37 cubic yards.

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

Step 4:- to determine how many bags of concrete you will need, divide the total cubic yards needed by the yields, as you know premixed bag of concrete available in 40lb, 60lb & 80lb. 40lb bag of concrete yields about 0.011 cubic yards, 60lb bag of concrete yields about 0.017 cubic yards and 80lb bag of concrete yields about 0.022 cubic yards.

**Number of bags of concrete for a 8×16 slab at 4 inch thick**

To determine how many bags of concrete you will need, divide the total cubic yards needed by the yields, at 4 inch thick, for a 8×16 slab you will need 1.56 yards of concrete, so number of 80lb bag of concrete = 1.56 ÷ 0.022 = 71 bags, No. of 60lb bag = 1.56 ÷ 0.017 = 92 bags & No. of 40lb bag = 1.56 ÷ 0.011 = 142 bags.

**Number of bags of concrete for a 8×16 slab at 5 inch thick**

To determine how many bags of concrete you will need, divide the total cubic yards needed by the yields, at 5 inch thick, for a 8×16 slab you will need 1.97 yards of concrete, so number of 80lb bag of concrete = 1.97 ÷ 0.022 = 90 bags, No. of 60lb bag = 1.97 ÷ 0.017 = 116 bags and No. of 40lb bag = 1.97 ÷ 0.011 = 179 bags.

**Number of bags of concrete for a 8×16 slab at 6 inch thick**

To determine how many bags of concrete you will need, divide the total cubic yards needed by the yields, at 6 inch thick, for a 8×16 slab you will need 2.37 yards of concrete, so number of 80lb bag of concrete = 2.37 ÷ 0.022 = 108 bags, No. of 60lb bag = 2.37 ÷ 0.017 = 140 bags and No. of 40lb bag = 2.37 ÷ 0.011 = 216 bags.

Regarding this, “how many bags of concrete do I need for a 8×16 slab?”, at 4 inches thick, generally you will need approximately either 92 bags of 60lb or 71 bags of 80lb of premixed concrete for a 8×16 slab, at 5 inches thick slab, either 116 bags of 60lb or 90 bags of 80lb premixed concrete are required, while at 6 inches thick slab, either 140 bags of 60lb or 108 bags of 80lb premixed concrete is necessary.

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**How much concrete do I need for a 8×16 slab**

Regarding this, “how much concrete do I need for a 8×16 slab?”, at 4 inches thick, generally you will need approximately 1.56 cubic yards or 42.24 cubic feet or 1.2 m3 (either 92 bags of 60lb or 71 bags of 80lb) of premixed concrete for a 8×16 slab, at 5 inches thick slab, 1.97 cubic yards or 53.25 cubic feet or 1.5 m3 (either 116 bags of 60lb or 90 bags of 80lb) of premixed concrete are required, while at 6 inches thick slab, 2.37 cubic yards or 64 cubic feet or 1.81 m3 (either 140 bags of 60lb or 108 bags of 80lb) of premixed concrete is necessary.

**How many yards of concrete do I need for a 8×16 slab**

Regarding this, “how many yards of concrete do I need for a 8×16 slab?, its depend on thickness of slab, assuming at 4 inches slab, generally you will need 1.56 cubic yards of premixed concrete for a 8×16 slab, at 5 inches thick slab, 1.97 cubic yards of premixed concrete are required, while at 6 inches thick slab, 2.37 cubic yards of premixed concrete is necessary.

**How many cubic feet of concrete do I need for a 8×16 slab**

Regarding this, “how many cubic feet of concrete do I need for a 8×16 slab?, its depend on thickness of slab, assuming at 4 inches slab, generally you will need 42.24 cubic feet of premixed concrete for a 8×16 slab, at 5 inches thick slab, 53.25 cubic feet of premixed concrete are required, while at 6 inches thick slab, 64 cubic feet of premixed concrete is necessary.

**How many m3 of concrete do I need for a 8×16 slab**

Regarding this, “how many m3 of concrete do I need for a 8×16 slab?, its depend on thickness of slab, assuming at 4 inches slab, generally you will need 1.2 cubic meter of premixed concrete for a 8×16 slab, at 5 inches thick slab, 1.5 cubic meter of premixed concrete are required, while at 6 inches thick slab, 2.37 cubic meter of premixed concrete is necessary.

**How many bags of concrete do I need for a 8×16 slab at 4″**

Regarding this, “how many bags of concrete do I need for a 8×16 slab at 4 inch thick?”, its depend on thickness of slab, at 4 inches thick, generally you will need approximately either 92 bags of 60lb or 71 bags of 80lb (1.56 cubic yards or 42.24 cubic feet or 1.2 m3) of premixed concrete for a 8×16 slab.

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**How many bags of concrete do I need for a 8×16 slab at 5″**

Regarding this, “how many bags of concrete do I need for a 8×16 slab at 5 inch thick?”, its depend on thickness of slab, at 5 inches thick, generally you will need approximately either 116 bags of 60lb or 90 bags of 80lb (1.97 cubic yards or 53.25 cubic feet or 1.5 m3) of premixed concrete for a 8×16 slab.

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**How many bags of concrete do I need for a 8×16 slab at 6″**

Regarding this, “how many bags of concrete do I need for a 8×16 slab at 6 inch thick?”, its depend on thickness of slab, at 6 inches thick, generally you will need approximately either 140 bags of 60lb or 108 bags of 80lb (2.37 cubic yards or 64 cubic feet or 1.81 m3) of premixed concrete for a 8×16 slab.

**Cost estimate for 8’×16’×4″ slab**

Pre-mixed concrete bags cost on average $5 per 80lb bag. There are 71 bags of 80 pound premix concrete are required for 8×16 slab at 4″ thick. Using pre-mixed bags to cover 8×16 (128 sq ft) at a depth of 4″, the estimated cost is $355 (71 × $5 = $355).

**Cost estimate for 8’×16’×5″ slab**

Pre-mixed concrete bags cost on average $5 per 80lb bag. There are 90 bags of 80 pound premix concrete are required for 8×16 slab at 5″ thick. Using pre-mixed bags to cover 8×16 (128 sq ft) at a depth of 5″, the estimated cost is $450 (90 × $5 = $450).

**Cost estimate for 8’×16’×6″ slab**

Pre-mixed concrete bags cost on average $5 per 80lb bag. There are 108 bags of 80 pound premix concrete are required for 8×16 slab at 6″ thick. Using pre-mixed bags to cover 8×16 (128 sq ft) at a depth of 6″, the estimated cost is $540 (108 × $5 = $540).