# How To Calculate Number Of Concrete Blocks In A Wall By Surface Area Method ?

### Calculation By Surface Area Method

#### Required Data:

• Surface area of the wall.
• Surface area of a standard concrete block.
• Surface area of openings in the wall.
##### Determine The Length & Height Of The Wall:

Let the Length of the wall = 10 feet.

The height of the wall = 10 feet.

##### Calculate The Surface Area Of The Wall:

We know, Surface Area = Length x Height

∴ Surface area of the wall = 10 x 10 = 100 sq. feet.

##### Step 3:

Calculate The Surface Area Of Openings:

If the wall has any openings such as doors, windows, etc, calculate the surface area of openings.

Let the wall has a window of 3′ x 3′

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

##### Step 4:

Subtract The Surface Area Of Openings From Surface Area Of Walls:

∴ Final Surface Area of wall = 100 – 9 = 91 sq.ft.

##### Step 5:

Calculate The Surface Area Of A Concrete Block With Mortar Allowance:

Let the block is 16″ x 8″ x 8″ and mortar allowance is 1″

∴ Surface Area of one block with mortar = (16+1) x (8+1)= 153 inch²

= 153/12×12 = 1.0625 sq.ft

##### Step 6:

Divide The Total Surface Area Of The Wall By Surface Area Of One Block:

∴ Number of blocks = Surface Area of wall/Surface Area of a block = 91/1.0625 = 86

Consider 5% wastage of concrete blocks.

So the total numbers of blocks required = 86 + (86 x 5/100) = 86 + 4 = 90.