How to Calculate Number of Concrete Blocks

• 

Concrete blocks are available in many sizes and shapes, and have a wide range of physical properties. They can be hollow or full, made from light cement or made of very dense aggregates.Calculating the amount of blocks needed for a building is a simple process that requires no prior knowledge of building or architecture.There are several methods for calculating the number of blocks in a wall. I will explain two simple methods for finding the total number of blocks for a wall.

1- Surface area method: Required data

1- Surface area of the wall.

2- Surface area of a standard concrete block.

3- Surface area of openings in the wall.

Step 1: Determine The Length & Height Of The Wall:

Let, the Length of the wall = 10 feet

The height of the wall = 10 feet.

Step 2: 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 door, 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: Substract 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 = length

* height =  (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 = 86Consider 5% wastage of concrete blocks.

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

2- Volume method: Required data

1- Volume of the wall.

2- Volume of a standard concrete block

3- Volume of openings in the wall.

Step 1: Determine The Width, Height, And Thickness Of The Wall:

Let, the width of the wall = 10 feet.

The height of the wall = 10 feet.

The thickness of the wall = 8″ = 0.67 feet. [ Thickness of wall will be same as the thickness of one concrete block] 

Step 2: Calculate The Volume Of The Wall:

We know, Volume = Width x Height x Thickness∴ Volume of the wall = 10 x 10 x 0.67 = 67 cubic feet.

Step 3: Calculate The Volume Of Openings:

If the wall has any openings such as door, windows etc, calculate the volume of openings.

Let the wall has a window of 3′ x 3′ x 0.67′ [ Thickness of the window will be same as the thickness of the wall] ∴ Volume of the window = 3 x 3 x 0.67 =6 cu. ft

Step 4: Substract The Volume Of Openings From Volume Of Walls:

Final volume of wall = 67 – 6 = 61 cu.ft.

Step 5: Calculate The Volume Of A Concrete Block With Mortar Allowance:

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

Volume of one block with mortar = (16+1) x (8+1) x 8 = 1224 inch3

[The mortal will be given on the upper side and one side of every concrete block] = 1224/12x12x12 = 0.70 cu.ft

Step 6: Divide The Total Volume Of The Wall By Volume Of One Block:

Number of blocks = Volume of wall/Volume of a block = 61/0.70 = 86Consider 5% wastage of concrete blocks.

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

Note:If the wall does not have any opening skip step 4, and just divide the surface area of wall by the surface area of one block.

•