Concrete (Cinder) Block Calculator

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Installation Overview:


One of the best building materials that you can use when you are considering doing a construction project is concrete. The truth is that this material is very used and suits perfectly utility buildings as well as the constructions of walls for foundations. So, this is one of the reasons why concrete block calculators are so popular. After all, they can save you a lot of time in terms of calculations.

One of the main characteristics of concrete blocks is that they tend to have holes in the middle. These holes serve multiple purposes. They don’t only reduce the material needed as well as their weight, and obviously, the cost is also lower.

Since the regular concrete block is made of both coal ash and cement, it is also known as a cinder block.

While we usually tend to refer to them as concrete blocks or cinder blocks, the reality is that they are concrete masonry units (CMUs).

#1: Concrete Masonry Unit (CMU):

The concrete masonry unit (CMU) is the regular size of the rectangular block that is mostly used in building construction.


As we have already mentioned, concrete blocks usually feature hollow centers not only to reduce their weight but also to improve insulation.

When you decide to use concrete or cinder blocks, you will be able to build the traditional masonry style of staggered blocks with courses or layers.

One of the things that you need to keep in mind is that you can find concrete blocks on many different sizes. In the United States, for example, 16 in × 8 in × 8 in (410 mm × 200 mm × 200 mm) is the most common nominal size and it measures a 3( in shorter to allow mortar joints. On the other hand, if you are in the United Kingdom or Ireland, the concrete blocks usually have 440 mm × 215 mm × 100 mm (17.3 in × 8.5 in × 3.9 in) without mortar joints. In Canada or New Zealand, the most common concrete blocks tend to feature 390 mm × 190 mm × 190 mm (15.4 in × 7.5 in × 7.5 in) without mortar joints.

Concrete blocks are usually tapered so that when you lay the block, its top surface has a bigger area to spread the mortar bed and to be easier to handle.

While most concrete masonry units include 2 cores, you will also be able to find blocks with 3 or 4 core units.

The main advantage of using cores is that they allow an easier insertion of steel reinforcement which adds an increased strength. After all, this will tie the individual blocks in the assembly process. In order to do it the right way, you need to ensure that you place the reinforcement in the right position by filling the cores with concrete, so that the block is bonded to the reinforcement.

While you don’t need to use reinforcement in all your construction projects, the truth is that it improves its ability to resist to lateral forces like seismic forces and wind load forces.

  • The Different Shapes Of Concrete Masonry Units (CMUs):

The reality is that depending on the kind of construction that you want to do, you have a wide range of concrete block shapes.

  • U-Shaped Blocks Or Knockout Blocks With Notches: This type of blocks provide you special construction features. With these blocks, you can easily build lintel assemblies or bond beams, and you can still use the horizontal reinforcing cement in the cavity.
  • Jamb Blocks: This type of blocks include a channel on the end and they allow the doors to be secured to wall assemblies.
  • Blocks With Grooved Ends: This type of blocks allow the building of control joints. So, you can have a filler material anchored between the un-mortared block ends.
  • Other Blocks: There are other types of blocks that come in a wide variety of decorative profiles as there are also others that are known as “bullnoses” because of the fact that they feature radiused corners.


The truth is that using concrete blocks allow you to have endless possibilities. Since they can be produced using different colors and textures, you can choose the ones that you prefer depending on the type of construction that you intend to do. In addition, concrete or cinder blocks offer you a great versatility and flexibility. You can have, for example, one block with 8*6 inches (200*410mm) that can be scored in the middle. So, this block is actually simulating an 8*8 inches (200*200mm) masonry, and has its groove filled with mortar and struck so it can match the true joints.

#2: How Many Concrete Blocks Do You Need For Your Building Construction?

The truth is that if you were already having some questions or doubts about how many concrete blocks you need for your building construction, you may now be wondering that it just got more complicated. After all, with so many different sizes and shapes, how can you be sure that you are buying the right number of concrete blocks?

The best way to be sure is to use a good concrete calculator that allows you to know exactly how many blocks you need to buy. Nevertheless, and even though concrete block calculators are trusty, we believe that it is always good to know what’s behind the scenes. Better said, it’s always a good idea to know how you get to the number of concrete blocks that you need for your building construction.

When you want to use a concrete block calculator, you will need to add some specific values. These include the dimensions of your building construction and the dimensions of the block that you are going to use, and the concrete block calculator will tell you the number of concrete blocks that you need to buy.

  • Determine The Size Of Your Building Construction:

The first thing that you need to do to know how many concrete blocks you need to build your construction is to know exactly its width and height, in inches.

Then, all you need to do is to determine the square footage which you can simply do by multiplying the width and the height of the building construction in feet.

  • Determine The Size Of The Concrete Block You Will Be Using:

Now that you already know the size of the building construction, you need to figure out the square footage of the block that you will be using.

Considering that the average concrete block size is 16 inches wide and 8 inches high, you just need to multiply the width by the height, and then divide the result by 144. This will give you the square footage.


According to the example that we have been using in this article, you are looking for the solution of (16*8)/144. The result is .89.

Please notice that this result will be different depending on the size of the concrete block that you want to use.

  • Finally, How Many Concrete Blocks Do You Need For Your Building Construction?

While you can (and should) use a good cinder block calculator, the truth is that all you need to do determine the number of concrete blocks you need for your building construction is to divide the wall square footage by the block square footage.

Please note that when you order your concrete blocks, you should make sure that you order between 5 and 10% more. The truth is that you may need to cut some for the edges as well as others can be broken.

#3: Estimating The Mortar You Need For Your Building Construction:

The truth is that the amount of mortar that you need for the joints in a concrete block construction will depend on the mix of mortar that you decide to use. Nevertheless, and to give you a better idea, you should know that on average, every 100 concrete blocks needs 3 bags of mortar.

So, in order to discover how many mortar bags you need for your building construction, you will need to divide the number of concrete blocks that you will install by 33.3.

In addition, you should also be aware that a standard mortar usually needs a 1:3 mortar to sand mix. So, this means that you will need to add 1 yd3 of sand to all seven bags of mortar.

#4: Estimating The Concrete Or Grout Fill:

As we already mentioned above, when you are building a construction using concrete blocks, you will need to fill their voids. But how much quantity of concrete or grout do you need to fill all the concrete blocks that you need?

Again, you will need to do some simple calculations in order to discover the exact amount that you need to order.

As we are trying to determine the amount of concrete or grout to fill the voids of the concrete blocks, you need to understand that we are now dealing with a volume unit. So, in order to estimate the concrete or gout fill in the concrete blocks, you will need to multiply the number of concrete blocks that you will be using and that you have already determined by the number of voids in the wall. 

To calculate the number of voids in the wall, you need to measure the width, height, and length of the voids in inches. However, you will also need to convert the inches into cubic inches. So, you will need to multiply the width, height, and length by the number of voids in the wall. These are usually 2. Then, in order to calculate the cubic yards of concrete that you need you just need to divide the cubic inches that you got by 46,656.

#5: The Different Installation Tools That You Will Need To Install A Concrete Block Building Construction:


While there are many different concrete block building constructions that you may want to do, the reality is that most people are looking to build a wall. So, with this in mind, we are now going to take a deeper look at all the installation tools that you will need to do the job right.

  • Mason Line: When you want to make sure that the wall you are building is straight and leveled and that the block is set at the right height, you need to ensure that you use a Mason Line.
  • Brick Trowel: When you need to place the mortar on top of the concrete blocks, you will need to create an even bed of mortar. This is the right tool to achieve it.
  • Jointer: When you want to ensure that the joins are cleaned and smooth, and with that professional look, you need to use a jointer.
  • Level: The worst thing that can happen to you when you are building a wall is that it doesn’t end up leveled and straight. So, you need to make sure that each block you use for the wall is in place on the right way. With this in mind, it’s always a good idea to have a level on your hand and the concrete block on the other. This will help you ensure that each block you add to your wall is not only straight as it is also leveled with the adjacent blocks.
  • Mixing Tube: When you want to make sure that your wheelbarrow is always cleaned, you should consider doing your mix mortar in a mixing tub.
  • Tape Measure: The truth is that your calculations may not be over yet. This is one of the reasons why we wanted to make sure that you understood all the calculations you need to do to order the right material and not simply using a cinder block calculator.

#6: The Most Common Concrete Block Sizes:

Besides the different types of concrete or cinder blocks that you can choose from, concrete blocks also have different sizes. The truth is that you will need to know exactly the size of the concrete blocks that you want to use on your building construction project since this will influence the number of blocks that you need.

The most common sizes of concrete blocks are 8 inches high by 8 inches wide, and 8 inches high by 16 inches wide. However, the thickness varies, and tends to vary a lot.

While the thickness of the concrete blocks that you choose doesn’t need to be taken into account when you simply want to know how many concrete blocks you need to build your wall, the truth is that it matters when you need to estimate the amount of mortar and masonry material that you need to actually build your wall.

Just like with the sizes of the concrete blocks, these also have more common thicknesses. These include 4, 6, 8, 10, 12, and 14 inches.