The dimensions of cinder blocks, also known as concrete masonry units (CMUs), can vary based on the specific ASTM standard and block type. The most common cinder block size in the United States is 8 inches by 8 inches by 16 inches. This is considered a nominal size, which means the block is referred to by these dimensions, but its actual dimensions may be slightly smaller to account for mortar joints.

Block manufacturers those that use cinders material of fly ash or bottom ash, coal dust, recycle aggregator, fine particles of ash after burning of coal as an aggregate material are known as cinder blocks in the United States. Its other name concrete block is also popular.

In United Kingdom, it is known as breeze blocks, which is a synonym of fly ash, and hollow blocks in the Philippines. In New Zealand & Canada they are known as concrete blocks. In New Zealand, they are also called construction blocks. In Australia, block are also called as Besser blocks and Besser bricks, because the Besser Company was a major supplier of machines that made concrete blocks. Clinker blocks use clinker as aggregate.

Concrete masonry unit in short form represented as CMU made of concrete, mixture of cement, sand and water or industrial wastage like coal dust, fly ash, recycled material, bottom ash, etc. There is a form of concrete masonry unit cinder block, concrete bricks, hollow cinder block, solid concrete block, lintel block, concrete stretcher block, concrete pillar blocks, partition concrete block, corner concrete block, concrete pillar block.

In United States, cinder or concrete block serve as economic building material and there is a wide range of construction application for many types of Residential, Public and industrial building. Due to sturdy and long lasting building material, architect and Engineer will recommended for house construction, retaining wall, security barriers etc and this is best choice.

**Cinder block dimensions**

Standard cinder blocks typically have dimensions of 8 inches in height, 8 inches in depth, and 16 inches in length. However, this dimension includes the length of the average mortar joint, which is 3/8 inch.

**Standard height, width & length of cinder block**

The standard height of most full size cinder blocks (CMU) is 8 inches high. And the standard length of most full size cinder blocks is 16 inches long. The variable dimension of a full size cinder block is it’s width. When masons refer to a 4 inch, 6 inch, 8 inch, 10 inch or 12 inch cinder block, they’re talking about the block’s width. Their face dimension are always 8 inches high x 16 inches long.

**Nominal and actual size of cinder block**

The cinder block manufactured in a variety of size, they are identified by their depth, such that thickness of wall that creates, for example 4″ CMU is normally 4″ wide while 10″ CMU is 10″ wide, represented as depth × height × length, it is also available in half size which helpful in reducing the need to cut cinder block at construction site.

Nominal size of cinder block is sum of size of block and thickness of mortar, cinder blocks available in many size, shape, and dimension.

The nominal size of a standard cinder block in the United States is 8 inches (20.32 cm) in height by 8 inches (20.32 cm) in depth and 16 inches (40.64 cm) in length. Their actual size measures a 3/8 inch shorter, it allowing for mortar joints, their actual size is 7 5/8″ × 7 5/8″ × 15 5/8″.

**Cinder block standard size**

The standard cinder block dimensions are 8 in. x 8 in. x 16 in (or 200×200×400 mm). However, this dimension includes the length of the average mortar joint, which is 3/8 in. This is nominal dimension of standard cinder block based on ASTM standard.

**Size/dimensions of cinder block based on ASTM standard (4″, 6″, 8″, 10″ & 12″)**

A full size of cinder block represented as a 4 inch wide, a 6 inch wide, an 8 inch wide, a 10 inch wide and a 12 inch wide have length of a 16 inch and height about 8 inch Full CMU represented as 4″×8″×16″, 6″×8″×16″, 8″×8″×16″, 10″×8″×16″ & 12″×8″×16″.

It is also available in half CMU length of 8 inch, represented as 4″×8″×8″, 6″×8″×8″, 8″×8″×8″, 10″×8″×8″ & 12″×8″×8″.

Typically, cinder block or concrete masonry units or CMU have nominal face dimensions of 8 in. (203 mm) by 16 in. (406 mm), available in nominal thicknesses of 4, 6, 8, 10, 12, 14, and 16 in. (102, 152, 203, 254, 305, 356, and 406 mm).

The most common nominal size for a cinder block is 16 inches long by 8 inches wide by 8 inches high or (203mm × 203mm × 405mm). Their actual sizes however are 7 5/8″ × 7 5/8″ × 15 5/8″ and the cinder blocks measure a 3/8 inch shorter, allowing for mortar joints.

The most common dimensions for a cinder block are approximately 8 In by 8 In by 16 In (203mm × 203mm × 405mm, or 20.3 cm x 20.3 cm x 40.5 cm ). Their actual sizes however are 7 5/8″ × 7 5/8″ × 15 5/8″ and the cinder blocks measure a 3/8 inch shorter, allowing for mortar joints.

**Size of 4″ full CMU or cinder block – 4″×8″×16″ or 100 mm × 200 mm × 400 mm**

The nominal size of 4 Inch or 4″ x 8″ x 16″ cinder block is 4 inches wide x 8 inches tall x 16 inches long and their actual size measure a 3/8 inch shorter, allowing for mortar joints. So, their actual dimensions are more apt to be 3 5/8-by-7 5/8-by-15 5/8.

Commonly available, size of 4″ full CMU or cinder block is 4 inches wide by 8 inches high by 16 inches long, which is represented in inch as 4 in × 8 in × 16 in or 100 × 200 × 400 in mm (wide × height× length). This is their nominal size, their actual size measure 3/8 inch shorter, allowing for mortar joints, has dimension of 3 5/8″ × 7 5/8″ × 15 5/8″ or approx 90 × 190 × 390 in mm.

**Size of 4″ half CMU or cinder block – 4″×8″×8″ or 100 mm × 200 mm × 200 mm**

The nominal size of 4 Inch or 4″ x 8″ x 8″ half cinder block is 4 inches wide x 8 inches tall x 8 inches long and their actual size measure a 3/8 inch shorter, allowing for mortar joints. So, their actual dimensions are more apt to be 3 5/8-by-7 5/8-by-7 5/8.

Commonly available, size of 4″ half CMU or cinder block is 4 inches wide by 8 inches high by 8 inches long, which is represented in inch as 4 in × 8 in × 8 in or 100 × 200 × 200 in mm (wide × height× length). This is their nominal size, their actual size measure 3/8 inch shorter, allowing for mortar joints, has dimension of 3 5/8″ × 7 5/8″ × 7 5/8″ or approx 90 × 190 × 190 in mm.

**Size of 6″ full CMU or cinder block – 6″×8″×16″ or 150 mm × 200 mm × 400 mm**

The nominal size of 6 Inch ( 6″ x 8″ x 16″ ) cinder block is 6 inches wide x 8 inches tall x 16 inches long and their actual size measure a 3/8 inch shorter, allowing for mortar joints. So, their actual dimensions are more apt to be 5 5/8-by-7 5/8-by-15 5/8.

Commonly available, size of 6″ full CMU or cinder block is 6 inches wide by 8 inches high by 16 inches long, which is represented in inch as 6 in × 8 in × 16 in or 150 × 200 × 400 in mm (wide × height× length). This is their nominal size, their actual size measure 3/8 inch shorter, allowing for mortar joints, has dimension of 5 5/8″ × 7 5/8″ × 15 5/8″ or approx 140 × 190 × 390 in mm.

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**Size of 6″ half CMU or cinder block – 6″×8″×8″ or 150 mm × 200 mm × 200 mm**

The nominal size of 6 Inch or 6″ x 8″ x 8″ half cinder block is 6 inches wide x 8 inches tall x 8 inches long and their actual size measure a 3/8 inch shorter, allowing for mortar joints. So, their actual dimensions are more apt to be 5 5/8-by-7 5/8-by-7 5/8.

Commonly available, size of 6″ half CMU or cinder block is 6 inches wide by 8 inches high by 8 inches long, which is represented in inch as 6 in × 8 in × 8 in or 150 × 200 × 200 in mm (wide × height× length). This is their nominal size, their actual size measure 3/8 inch shorter, allowing for mortar joints, has dimension of 5 5/8″ × 7 5/8″ × 7 5/8″ or approx 140 × 190 × 190 in mm.

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**Size of 8″ full CMU or cinder block – 8″×8″×16″ or 200 mm × 200 mm × 400 mm**

The nominal size of 8 Inch ( 8″ x 8″ x 16″ ) cinder block is 8 inches wide x 8 inches tall x 16 inches long and their actual size measure a 3/8 inch shorter, allowing for mortar joints. So, their actual dimensions are more apt to be 7 5/8-by-7 5/8-by-15 5/8.

Commonly available, size of 8″ full CMU or cinder block is 8 inches wide by 8 inches high by 16 inches long, which is represented in inch as 8 in × 8 in × 16 in or 200 × 200 × 400 in mm (wide × height× length). This is their nominal size, their actual size measure 3/8 inch shorter, allowing for mortar joints, has dimension of 7 5/8″ × 7 5/8″ × 15 5/8″ or approx 190 × 190 × 390 in mm.

**Size of 8″ half CMU or cinder block – 8″×8″×8″ or 200 mm × 200 mm × 200 mm**

The nominal size of 8 Inch or 8″ x 8″ x 8″ half cinder block is 8 inches wide x 8 inches tall x 8 inches long and their actual size measure a 3/8 inch shorter, allowing for mortar joints. So, their actual dimensions are more apt to be 7 5/8-by-7 5/8-by-7 5/8.

Commonly available, size of 8″ half CMU or cinder block is 8 inches wide by 8 inches high by 8 inches long, which is represented in inch as 8 in × 8 in × 8 in or 200 × 200 × 200 in mm (wide × height× length). This is their nominal size, their actual size measure 3/8 inch shorter, allowing for mortar joints, has dimension of 7 5/8″ × 7 5/8″ × 7 5/8″ or approx 190 × 190 × 190 in mm.

**Size of 10″ full CMU or cinder block – 10″×8″×16″ or 250 mm × 200 mm × 400 mm**

The nominal size of 10 Inch ( 10″ x 8″ x 16″ ) cinder block is 10 inches wide x 8 inches tall x 16 inches long and their actual size measure a 3/8 inch shorter, allowing for mortar joints. So, their actual dimensions are more apt to be 9 5/8-by-7 5/8-by-15 5/8.

Commonly available, size of 10″ full CMU or cinder block is 10 inches wide by 8 inches high by 16 inches long, which is represented in inch as 10 in × 8 in × 16 in or 250 × 200 × 400 in mm (wide × height× length). This is their nominal size, their actual size measure 3/8 inch shorter, allowing for mortar joints, has dimension of 9 5/8″ × 7 5/8″ × 15 5/8″ or approx 240 × 190 × 390 in mm.

**Size of 10″ half CMU or cinder block – 10″×8″×8″ or 250 mm × 200 mm × 200 mm**

The nominal size of 10 Inch or 10″ x 8″ x 8″ half cinder block is 10 inches wide x 8 inches tall x 8 inches long and their actual size measure a 3/8 inch shorter, allowing for mortar joints. So, their actual dimensions are more apt to be 9 5/8-by-7 5/8-by-7 5/8.

Commonly available, size of 10″ half CMU or cinder block is 10 inches wide by 8 inches high by 8 inches long, which is represented in inch as 10 in × 8 in × 8 in or 250 × 200 × 200 in mm (wide × height× length). This is their nominal size, their actual size measure 3/8 inch shorter, allowing for mortar joints, has dimension of 9 5/8″ × 7 5/8″ × 7 5/8″ or approx 240 × 190 × 190 in mm.

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**Size of 12″ full CMU or cinder block – 12″×8″×16″ or 300 mm × 200 mm × 400 mm**

The nominal size of 12 Inch or 12″ x 8″ x 16″ cinder block is 12 inches wide x 8 inches tall x 16 inches long and their actual size measure a 3/8 inch shorter, allowing for mortar joints. So, their actual dimensions are more apt to be 11 5/8-by-7 5/8-by-15 5/8.

Commonly available, size of 12″ full CMU or cinder block is 12 inches wide by 8 inches high by 16 inches long, which is represented in inch as 12 in × 8 in × 16 in or 300 × 200 × 400 in mm (wide × height× length). This is their nominal size, their actual size measure 3/8 inch shorter, allowing for mortar joints, has dimension of 11 5/8″ × 7 5/8″ × 15 5/8″ or approx 290 × 190 × 390 in mm.

**Size of 12″ half CMU or cinder block – 12″×8″×8″ or 300 mm × 200 mm × 200 mm**

The nominal size of 12 Inch or 12″ x 8″ x 16″ half cinder block is 12 inches wide x 8 inches tall x 8 inches long and their actual size measure a 3/8 inch shorter, allowing for mortar joints. So, their actual dimensions are more apt to be 11 5/8-by-7 5/8-by-7 5/8.

Commonly available, size of 12″ half CMU or cinder block is 12 inches wide by 8 inches high by 8 inches long, which is represented in inch as 12 in × 8 in × 8 in or 300 × 200 × 200 in mm (wide × height× length). This is their nominal size, their actual size measure 3/8 inch shorter, allowing for mortar joints, has dimension of 11 5/8″ × 7 5/8″ × 7 5/8″ or approx 290 × 190 × 190 in mm.

**Conclusion:-**

The most common nominal dimensions for a cinder block is **16 inches long by 8 inches wide by** **8 inches high** or (203mm × 203mm × 405mm). Their actual sizes however are 7 5/8″ × 7 5/8″ × 15 5/8″ and the cinder blocks measure a 3/8 inch shorter, allowing for mortar joints.