# Block wall calculation | Find how many blocks you need

Some special things to remember

Concrete block/cinder block/concrete masonry/ CMU/ breeze block. These all are blocks.

CMU stands for – concrete masonry unit.

ASTM stands for – American Society for Testing and Materials.

## How to calculate the number of concrete blocks in a wall

There are two methods to calculate the number of concrete blocks in a wall.

1. Surface area method
2. Volume method

At first, we are going to calculate the number of concrete blocks in a wall using the surface area method.

If you want to calculate the number of concrete blocks for a wall then you will have to collect some data before.

Step 1

• What is the surface area of the wall?
• What is the surface area of the concrete blocks?
• What is the surface area of the openings in the wall?

### How many concrete blocks are needed for 10′ × 10′ or 100 sq ft wall

As we are finding the number of concrete blocks for 100 sq. Ft.

Step 2

First, decide the length and height of the wall then calculate.

So, the length of the wall is 10 feet.

The height of the wall is 10 feet.

Step 3

Now, the formula for calculating the surface area of the wall is

Surface area = l × h. In which l = length and h = height

Now, the surface area of the wall = 10 × 10 = 100 sq. Ft.

Step 4

It’s time to calculate the surface area of the openings.

This opening can be for Windows, doors, etc.

3′ × 3′

Suppose we have a window on the wall that is 3′ × 3′

So, the surface area of the window = 3 × 3 = 9 ft.

Step 5

Now if you want to get the actual size then subtract the opening from the surface area of the wall.

After subtraction we get,

100 – 9 = 91 sq. Ft.

Step 6

This time we need to calculate the surface area of the concrete block with mortar.

As you know, the standard size of concrete block is = 16″ × 8″ × 8″ and the allowance thickness of the mortar = 1″

Now the surface area of the one concrete block with mortar = (16 +1) × (8 +1) = 153″

So, (153/12) × 12 = 1.0625 ft.

Step 7

Now after dividing the total surface area of the wall by the surface area of the one concrete block

No. Of blocks = surface area of the wall ÷ surface area of a block
= 91÷ 1.0625 = 85.6470 or it can be written as 86.

Suppose there can be a 2 % wastage of concrete blocks.

Therefore, the whole number of concrete blocks needed for a 100 sq. ft wall

= 86 + (86 × 2 / 100 ) = 86 + 2 = 90

### Calculate the number of concrete blocks for a 10 × 10 or 100 sq. ft wall by using the Volume method

Step 1

If you want to calculate the number of concrete blocks for a wall then you will have to collect some data before.

1. What is the volume of the wall?
2. What is the volume of the standard concrete blocks?
3. What is the volume of the openings in the wall?

Step 2

First fix the height and the thickness of the wall.

Suppose, the width, height, and thickness of the wall are 10′, 10′, and 0.67′ respectively.

Note: The thickness of one concrete block is as same as the thickness of the wall.

Step 3

Now calculate the volume of the wall.

The formula for calculation of the volume of the wall = W × H × T ( with × height × thickness )

Now, volume of the wall = 10 × 10 × 0.67 = 67 cubic ft.

Step 4

Now find the volume of the wall of the opening. This opening can be for Windows, doors, etc.

Suppose we have window openings that are 3′ × 3′

So now, after calculating the volume of the opening window = 3 × 3 × 0.67 = 6 cubic ft. we get.

Step 5

Now if you want to get the actual size then subtract the opening from the volume of the wall.

Now we find, 67 – 6 = 61 cubic ft. It is the final volume of the wall.

Step 6

This time we need to calculate the volume of the concrete block with mortar.

As you know, the standard size of concrete block is = 16″ × 8″ × 8″ and the allowance of the mortar = 1″

Now the volume of the one concrete block with mortar = (16 +1 ) × ( 8 + 1) × 8 = 1224 inches, which is equal to 1224/12×12×12 = 0.70 cubic ft.

Step 7

Now after dividing the total volume of the wall by the volume of the one concrete block

No. Of blocks = volume of the wall ÷ volume of a block
= 61 ÷ 0.70 = 86

Suppose there can be a 2 % wastage of concrete blocks.

So total number of the concrete blocks needed = 86 + (86 × 2/100) = 86 + 2 = 88

One thing you have to remember here is if there is no window available then please skip step 5.

#### Conclusion

In this article, we have discussed how to calculate the number of blocks required for a 10 × 10 sq ft wall. I hope through this article you will gain some knowledge about some little calculations.