Cinder block dimensions – Cinder block sizes

What are the most common Cinder block dimensions/Cinder block sizes available. Cinder blocks come in size 4, 6, 8, 10 and 12. These sizes are based on the thickness of the blocks in inches i.e. 8 inch cinder block will be 8 inch wide on its outer rim. This is after plaster is applied to both ends of the block. Without plaster the width of the block will be 19.3675 cm (7.625 inch) or in masonry terms 7 5/8″. The block is smaller than the mentioned width so that when you make a room the width of the wall remains the same after the plaster is applied. This ensures that the size of a room doesn’t decrease from the actual planned size.

Don’t get confused by the markings in fractions, this is just a way of writing stuff in feet and inches. The architects, civil engineers and masons were accustomed to using these markings so they stuck to this method. Just use a calculator and a value converter to extract the exact sizes in meter and centimeter.

Cinder block dimensions

What is the standard size of a cinder block?

I have mentioned below the standard aka nominal sizes of the cinder blocks below.

Size 4Size 6Size 8Size 10Size 12
Width4681012
Height88888
Length1616161616
Cinder block dimensions/sizes: Cinder block standard sizes of full blocks

The second table shows the sizes of half blocks. For half blocks the length is the only parameter that changes.

Size 4Size 6Size 8Size 10Size 12
Width4681012
Height88888
Length88888
Cinder block dimensions/sizes: Cinder block standard sizes of half blocks

Those are the standard sizes that you will find to be mentioned on every hardware store. But the actual sizes of the blocks are smaller as I had mentioned earlier. In the tables below I have mentioned the actual sizes of full and half blocks.

Size 4Size 6Size 8Size 10Size 12
Width3-5/85-5/87-5/89-5/811-5/8
Height7-5/87-5/87-5/87-5/87-5/8
Length15-5/815-5/815-5/815-5/815-5/8
Cinder block dimensions/sizes: Cinder block actual sizes of full blocks
Size 4Size 6Size 8Size 10Size 12
Width3-5/85-5/87-5/89-5/811-5/8
Height7-5/87-5/87-5/87-5/87-5/8
Length7-5/87-5/87-5/87-5/87-5/8
Cinder block dimensions/sizes: Cinder block actual sizes of half blocks

The below sections explain the tables in clear and easy terms.

What is the size of a 12 inch cinder block?

In plain terms the standard/nominal size of size 12 cinder block is 12 x 8 x 16 where 12 is the width, 8 is the height and 16 is the length of the block respectively. The actual size of the same block is 11-5/8 x 7-5/8 x 15-5/8 respectively. Similarly the standard size of a size 12 half block will be 12 x 8 x 8, in which 12 is the width, 8 is the height, and 8 is the length respectively. The actual sizes of the half block will be 11-5/8 x 7-5/8 x 7-5/8.

What is the size of a 10 inch cinder block?

In plain terms the standard/nominal size of size 10 cinder block is 10 x 8 x 16 where 10 is the width, 8 is the height and 16 is the length of the block respectively. The actual size of the same block is 9-5/8 x 7-5/8 x 15-5/8 respectively. Similarly the standard size of a size 10 half block will be 10 x 8 x 8, in which 10 is the width, 8 is the height, and 8 is the length respectively. The actual sizes of the half block will be 9-5/8 x 7-5/8 x 7-5/8.

What is the size of a 8 inch cinder block?

In plain terms the standard/nominal size of size 8 cinder block is 8 x 8 x 16 where 8 is the width, 8 is the height and 16 is the length of the block respectively. The actual size of the same block is 7-5/8 x 7-5/8 x 15-5/8 respectively. Similarly the standard size of a size 8 half block will be 8 x 8 x 8, in which 8 is the width, 8 is the height, and 8 is the length respectively. The actual sizes of the half block will be 7-5/8 x 7-5/8 x 7-5/8.

What is the size of a 6 inch cinder block?

In plain terms the standard/nominal size of size 6 cinder block is 6 x 8 x 16 where 6 is the width, 8 is the height and 16 is the length of the block respectively. The actual size of the same block is 5-5/8 x 7-5/8 x 15-5/8 respectively. Similarly the standard size of a size 6 half block will be 6 x 8 x 8, in which 6 is the width, 8 is the height, and 8 is the length respectively. The actual sizes of the half block will be 5-5/8 x 7-5/8 x 7-5/8.

What is the size of a 4 inch cinder block?

So in plain terms the standard/nominal size of size 4 cinder block is 4 x 8 x 16 where 4 is the width, 8 is the height and 16 is the length of the block respectively. The actual size of the same block is 3-5/8 x 7-5/8 x 15-5/8 respectively. Similarly the standard size of a size 4 half block will be 4 x 8 x 8, in which 4 is the width, 8 is the height, and 8 is the length respectively. The actual sizes of the half block will be 3-5/8 x 7-5/8 x 7-5/8.

How do I calculate concrete blocks required for my project ?

First you would need to calculate the wall height and width. Then find out the area of the wall by multiplying the width times the height. This will give you the area of one wall. If you are constructing multiple walls or a room you would need to add the area of each individual wall to get the area of all the walls of the room.

Next you have to find the area of the block. You can do this by using the following formula.

Block square footage/area = A × B 

where A is the length, and B is the height of the block. For a standard block it would be 16 x 8 = 128 sq. ft.

To get the no. of blocks required for the project just divide the area of all the walls with the area of the block, for e.g. if the area of a wall is 14,400 inches then divide it by 128 inches ( the area of the block ). This comes out to be 112.5. So you would need 113 blocks for the project. In actuality always add a bunch more blocks than are required. At least 10 to 20 percent more to account for breakage and other things.

Please keep in mind that you need to account for the units. If you are calculating the area of the block in inches than you have to also calculate the area of the wall in inches as well. If you calculate the area of the wall in feet then you would have to calculate the area of the block in feet as well. Hope this article helped you.

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References

Engineering Toolbox, (2010). Masonry Blocks – Dimensions. [online] Available at: https://www.engineeringtoolbox.com/concrete-masonry-blocks-d_1731.html

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