How to calculate the Number of Concrete Blocks in the Wall?

There are various methods for calculating the number of blocks in the wall. In this article, we will see two simple methods for calculating the number of blocks used in the wall.

1. Surface Area Method
2. Volume Method

How to calculate the number of Blocks by Surface Area Method?

1. The surface area of the wall
2. Surface area of the standard concrete block
3. The surface area of openings in the wall

Step 1

The Length & Height of the Wal

Take as Length of the wall = 10 feet

The height of the wall = 10 feet

Step 2

Now calculate the surface area of the wall

Surface Area = Length x Height

Surface Area of the wall = 10 x 10 = 100 sq. feet.

Step 3

Now calculate the Surface Area of Openings

The openings like a door, windows, etc.

Let the wall has window 3’ x 3’

Surface area of the window = 3 x 3 = 9 sq. ft

Step 4

Now subtract the openings from the surface area of the Wall

Final surface area = 100-9= 91 sq. feet

Step 5

Now calculate the surface area of concrete block with mortar

The standard block is 16” x 8” x 8” and mortar allowance is 1”

Surface area of block with mortar = (16+1) x (8+1) = 153 inch²

153/12 x 12 = 1.0625 sq. ft

Step 6

Now divide the total surface area of the wall by the surface area of one block

Number of blocks= surface area of Wall/Surface area of the block

91/1.0625=86

Now consider 5% wastage of concrete blocks

Total number of blocks required = 86 + (86 x 5/100) = 86 + 4 = 90

Now calculate by Volume Method

1. The volume of the wall
2. Volume of the standard concrete block
3. The volume of the openings in the wall

Step 1

First determine the Width, Height, and Thickness of the Wall

Width of the wall = 10 feet

Height of the wall = 10 feet

Thickness of the wall = 8” = 0.67 feet. (Thickness of wall is the same as the thickness of one concrete block)

Step 2

Now the calculate the volume of the wall

Volume = Width x Height x Thickness

Volume of the wall = 10 x 10 x 0.67 = 67 cubic feet

Step 3

The volume of the Openings

The openings like a door, windows, etc.,

Now calculate the volume of the window = 3 x 3 x 0.67 = 6 cubic feet

Step 4

Subtract the volume of the Openings from Volume of Walls

Final Volume of wall = 67 – 6 = 61 cubic feet

Step 5

Now calculate the volume of the concrete block with the Mortar allowance

The concrete block is 16” x 8” x 8” and mortar allowance is 1”

The volume of one block with mortar = (16+1) x (8+1) x 8 = 1224 inch³ (Mortar is applied on upper and one side of every block)

1224/12 x 12 x 12 = 0.70 cubic feet

Step 6

Divide the total volume of a wall by volume of one block

Number of blocks = Volume of Wall/ Volume of Block

61/0.70 = 86

Now consider 5% wastage of concrete blocks

Total number of blocks required = 86 + (86 x 5/100) = 86 + 4 = 90

Note that if there are no openings in the wall, skip step 4.