# How to calculate the quantity of concrete in slab, column, patio & retaining wall

To calculate the quantity of concrete needed for a slab, column, patio, or retaining wall, you’ll need to follow these general steps:

1. Calculate Area:Measure the length and width of the slab in meters. Multiply the length by the width to get the area in square meters.

2. Determine Thickness:Measure the thickness of the slab in meters.

3. Calculate Volume: Multiply the area by the thickness to get the volume in cubic meters.

Concrete is one of the most important building material made of mixture of cement, sand, aggregate and water in required proportion to form different structure like beam, column, slab, footing, staircase in residential and commercial building. And also it can be used in casting of patio, retaining wall, pile, concrete blocks, isolated footing, driveway, and other industrial projects like power plant, Bridge, dams, reservoir, tunnels etc.

You should also visits:-

1)what is concrete and its types and properties

2) concrete quantity calculation for staircase and its formula

Concrete is good in compression and weak in tension, to enhance the tensile strength of concrete various grade and strength of reinforcement bar embedded in it. Their strength is measured in different International unit like N/mm2, psi, MPa.

In this article we know about How to calculate the quantity of concrete in slab, column, patio & retaining wall | how to calculate quantity of concrete in circular column | how to calculate quantity of concrete in retaining wall | how to calculate concrete quantity in footing.

## How to calculate the quantity of concrete

If you want to start new projects made of concrete like driveway, patio, retaining wall, slab, column, beam, staircase, footing, etc, the question is arises in mind how much concrete you need? To determine how much concrete you need, we should follow different steps:-

How to calculate the quantity of concrete:-

1) determined how thick you want the concrete for different structure.

2) measure the length and width of concrete structure.

3) multiplying the Length and width of concrete structure to get square footage.

4) if required, convert thickness of concrete structure inch to feet.

5) calculate the volume of concrete structure in cubic feet by multiplying square footage and thickness.

6) if required, convert cubic feet of concrete into cubic yard by multiplying 0.037 to determine concrete quantity in cubic yard.

One cubic yard is measured by 3 feet long by 3 feet width by 3 feet thickness, equal as 3× 3× 3 = 27 cubic feet and vice versa 1 cubic feet = 1/27 = 0.037 cubic yards.

EXAMPLE 1

FOR PATIO

How to calculate concrete quantity for 10′ by 10′ Patio

● Consider thickness of Patio should be 4 inch thick.

● Calculate area of patio in square footage as 10’× 10′ = 100 sq ft.

● Conver thickness 4 inch into feet, as 4/12 = 0.33 foot

● Multiplying square footage area of Patio and their thickness as 100× 0.33 = 33 cubic feet.

● To determine quantity of concrete in Patio, convert 33 cubic feet into cubic yard by multiplying 0.037 as 33× 0.037 = 1.221 cubic yards. Therefore you will need 1.221 cubic yards of concrete for 10’× 10′ Patio of 4 inch thick.

How many bags of concrete do i need for a 10’× 10′ Patio?

As we know 40 pounds a bag of concrete yields 0.011 cubic yards, 60 pounds a bag of concrete yields 0.017 cubic yards and 80 pounds a bag of concrete yields 0.022 cubic yards.

As per calculation you need 1.221 cubic yards of concrete for 10’× 10′ Patio of 4 inch thick. Converting into bag of concrete, you will need,40 lb bag of concrete = 1.221/ 0.011 = 111 bags, 60 lb bag of concrete = 1.221/ 0.017 = 72 bags and 80 lb bag of concrete = 1.221/ 0.022 = 56 bags, therefore you need 111 bags of 40 lb concrete, 72 bags of 60 lb concrete or 56 bags of 80 lb concrete for a 10’× 10′ Patio of 4 inch thick.

For 5 inch thick, 10’× 10′ (100 sq ft) Patio you will need about 1.54 cubic yards or 41.625 cubic feet of concrete or 140 bags of 40 lb concrete, 91 bags of 60 lb concrete or 70 bags of 80 lb concrete.

For 6 inch thick, 10’× 10′ (100 sq ft) Patio you will need about 1.85 cubic yards or 50 cubic feet of concrete or 168 bags of 40 lb concrete, 109 bags of 60 lb concrete or 84 bags of 80 lb concrete.

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EXAMPLE 2

FOR SLAB

How to calculate concrete quantity for 10′ by 20′ slab

● Consider thickness of slab should be 4 inch thick.

● Calculate area of slab in square footage as 10’× 20′ = 200 sq ft.

● Conver thickness 4 inch into feet, as 4/12 = 0.33 foot

● Multiplying square footage area of slab and their thickness as 200× 0.33 = 66 cubic feet.

● To determine quantity of concrete in slab, convert 66 cubic feet into cubic yard by multiplying 0.037 as 66× 0.037 = 2.442 cubic yards. Therefore you will need 2.442 cubic yards of concrete for 10’× 20′ slab of 4 inch thick.

How many bags of concrete do i need for a 10’× 20′ slab?

As we know 40 pounds a bag of concrete yields 0.011 cubic yards, 60 pounds a bag of concrete yields 0.017 cubic yards and 80 pounds a bag of concrete yields 0.022 cubic yards.

As per calculation you need 2.442 cubic yards of concrete for a 10’× 20′ slab of 4 inch thick. Converting into bag of concrete, you will need,40 lb bag of concrete = 2.442/ 0.011 = 222 bags, 60 lb bag of concrete = 2.442/ 0.017 = 144 bags and 80 lb bag of concrete = 2.442/ 0.022 = 111 bags, therefore you need 222 bags of 40 lb concrete, 144 bags of 60 lb concrete or 111 bags of 80 lb concrete for a 10’× 20′ slab of 4 inch thick.

For 5 inch thick, 10’× 20′ (200 sq ft) slab you will need about 3.083 cubic yards or 83.33 cubic feet of concrete or 280 bags of 40 lb concrete, 181 bags of 60 lb concrete or 140 bags of 80 lb concrete.

For 6 inch thick, 10’× 20′ (200 sq ft) slab you will need about 3.7 cubic yards or 100 cubic feet of concrete or 336 bags of 40 lb concrete, 218 bags of 60 lb concrete or 168 bags of 80 lb concrete.

EXAMPLE 3

IN FOOTING

How to calculate quantity of concrete in footing

● Consider thickness of footing, that should be 12 inch thick.

● Calculate area of footing in square footage, consider minimum length and width of footing is 12 inch, so square footage = 1× 1 = 1 sq ft concrete

● Convert thickness 12 inch into feet, as 12/12 = 1 foot

● Multiplying square footage area of footing and their thickness as 1× 1 = 1 cubic feet.

● To determine quantity of concrete in footing, convert 1 cubic feet into cubic yard by multiplying 0.037 as 1× 0.037 = 0.037 cubic yards. Therefore you will need 1 cubic yards of concrete for 1’× 1’× 1′ footing.

How many bags of concrete do I need for a footing?

As we know 40 pounds a bag of concrete yields 0.297 cubic foot, 60 pounds a bag of concrete yields 0.459 cubic foot and 80 pounds a bag of concrete yields 0.594 cubic foot.

For one cubic feet of concrete in footing, you will need about 3.36 bags of 40 lb concrete (1/ 0.297 = 3.36 bags concrete), 2.17 bags of 60 lb concrete (1/ 0.459 = 2.17 bags concrete) or 1.68 bags of 80 lb concrete (1/ 0.594 = 1.68 bags concrete).

EXAMPLE 4

FOR RETAINING WALL

How to calculate concrete quantity for 10′ by 20′ retaining wall

● Consider thickness of retaining wall should be 4 inch thick.

● Calculate area of retaining wall in square footage by multiplying length and height as 10’× 20′ = 200 sq ft.

● Conver thickness 4 inch into feet, as 4/12 = 0.33 foot

● Multiplying square footage area of retaining wall and their thickness as 200× 0.33 = 66 cubic feet.

● To determine quantity of concrete for retaining wall, convert 66 cubic feet into cubic yard by multiplying 0.037 as 66× 0.037 = 2.442 cubic yards. Therefore you will need 2.442 cubic yards of concrete for 10’× 20′ retaining wall of 4 inch thick.

How many bags of concrete do i need for a 10’× 20′ retaining wall?

As we know 40 pounds a bag of concrete yields 0.011 cubic yards, 60 pounds a bag of concrete yields 0.017 cubic yards and 80 pounds a bag of concrete yields 0.022 cubic yards.

As per calculation you need 2.442 cubic yards of concrete for a 10’× 20′ retaining wall of 4 inch thick. Converting into bag of concrete, you will need,40 lb bag of concrete = 2.442/ 0.011 = 222 bags, 60 lb bag of concrete = 2.442/ 0.017 = 144 bags and 80 lb bag of concrete = 2.442/ 0.022 = 111 bags, therefore you need 222 bags of 40 lb concrete, 144 bags of 60 lb concrete or 111 bags of 80 lb concrete for a 10’× 20′ retaining wall of 4 inch thick.

For 5 inch thick, 10’× 20′ (200 sq ft) retaining wall, you will need about 3.083 cubic yards or 83.33 cubic feet of concrete or 280 bags of 40 lb concrete, 181 bags of 60 lb concrete or 140 bags of 80 lb concrete.

For 6 inch thick, 10’× 20′ (200 sq ft) retaining wall, you will need about 3.7 cubic yards or 100 cubic feet of concrete or 336 bags of 40 lb concrete, 218 bags of 60 lb concrete or 168 bags of 80 lb concrete.

EXAMPLE 5

IN Column

How to calculate quantity of concrete in column

For rectangular Column

● Consider A rectangular column height of 10 foot and their dimension length and breadth is 9″× 12″.

● Convert all dimensions in foot, as length= 9/12 = 0.75 foot, and width 12/12 = 1 foot

● calculate surface area of rectangular column as 0.75 × 1 = 0.75 square footage

● To determine quantity of concrete in rectangular column, you will multiply square footage surface area of column and their height as 0.75 sq ft × 10 ft = 7.5 cubic foot.

For Square Column

● Consider A square column height of 10 foot and their dimension length and breadth is 12″× 12″.

● Convert all dimensions in foot, as length= 12/12 = 1 foot, and width 12/12 = 1 foot

● calculate surface area of square column as 1 × 1 = 1 square footage

● To determine quantity of concrete in square column, you will multiply square footage surface area of column and their height as 1 sq ft × 10 ft = 10 cubic foot.

For Circular Column

● Consider A Circular column height of 10 foot and their diameter is 12 inch

● Convert all dimensions in foot, as diameter is 12/12 = 1 foot

● calculate surface area of circular column as πD^2/4 = (3.14 × 1 ×1)/4 = 0.785 square footage

● To determine quantity of concrete in circular column, you will multiply square footage surface area of column and their height as 0.785 sq ft × 10 ft = 7.85 cubic foot.

For Hexagonal Column

● Consider A hexagonal column height of 10 foot and their sides are equal to 3 inch

● Convert all dimensions in foot, as sides is 3/12 = 0.25 foot

● hexagonal shape column is combination of six equilateral triangle, calculate surface area of hexagonal column as 6 × √3/4 S^2 = 3√3/2 S^2 = (3 × 1.732/2) 0.25 × 0.25 = 0.1624 square footage

● To determine quantity of concrete in hexagonal column, you will multiply square footage surface area of column and their height as 0.1624 sq ft × 10 ft = 1.624 cubic foot.

EXAMPLE 6

IN BEAM

How to calculate quantity of concrete in beam

● Consider A rectangular beam length of 10 foot and their dimension width and thickness is 9″× 12″.

● Convert all dimensions in foot, as length= 9/12 = 0.75 foot, and width 12/12 = 1 foot

● calculate surface area of beam as 0.75 × 1 = 0.75 square footage

● To determine quantity of concrete in beam, you will multiply square footage surface area of beam and their lenth as 0.75 sq ft × 10 ft = 7.5 cubic foot.