Concrete Block Calculator

If your plan is to build a concrete block wall, make sure to use this concrete block calculator before you lay the first stone! Is the question, "How many concrete blocks do I need for this project?" on your mind? If so, this tool will surely be of great help to you. You can use it to find out how many cinder blocks are needed for a wall of a particular size, estimate the required amount of mortar, and also get an idea of how much the materials needed for your project will cost based on the average concrete blocks cost.

Our calculator is simple and intuitive to use. To estimate everything your project needs, follow these instructions:

1. Input the dimensions of the concrete block wall you're building, that is, its width and height. We need these parameters to determine the wall's area.
2. Decide whether you want to choose a preset block size, or input a custom one:
   • The preset block sizes are the six most common types you can find in the U.S.A. Feel free to use our length converter if you want to know what they are in metric. All you need to do here is pick the size you want.
   • If you pick custom size, you need to provide the calculator with the height and width of a single concrete block. An illustration of a wall segment will appear to show exactly which dimensions are needed to avoid confusion.
   • In both cases, you will see the total number of concrete blocks needed for your project.
3. Calculate the concrete blocks cost, which is done by inputting the price of a single block.
4. Have a look at the mortar estimation field by clicking on the Mortar estimation heading. On average, it takes three standard mortar bags to bond 100 concrete blocks together. Please note that this is a rough estimation, and you might need to calculate it separately using factors such as mortar type.

If, after using our calculator, you're still thinking, "But how did they find out how many concrete blocks I need?", we are happy to walk you through the process!

When calculating the number of blocks needed, the first thing to do is to calculate the size of your concrete block wall. To do so, you need to multiply the wall's height and width:

wall size = wall height × wall width

To calculate the number of blocks, you need to divide the total area of the wall by the area of a single block:

number of blocks needed = wall area / block area

block area = block height × block width

Then you need to calculate your concrete block costs; just multiply the number of cinder blocks by the price per single block:

concrete block costs = price per block × number of blocks

When it comes to estimating the mortar needed, a good rule of thumb is that three standard bags will typically cover 100 blocks. To calculate the number of such bags, you need to divide the number of blocks by 33.3:

mortar bags estimation = number of blocks needed / 33.3

You can also use our cement calculator to find how much cement and sand you'll need if you decide to mix your own mortar for your concrete blocks.

With the equations presented above, you can answer the question "How many concrete blocks do I need?" without too much trouble. Just in case, we will go through an example to clear up any doubts that may still remain.

Let's say your wall is to be 10 feet high and 50 feet wide. With these dimensions, it will cover 10 × 50 = 500 square feet. If you use a standard 16" x 8" block, the area of a single block is 128 square inches, and you will need 563 concrete blocks, as 500 ft² / 128 in² = 72,000 in² / 128 in² = 562.5 (rounding up to the nearest whole number).

If one cinder block costs $1.5, you will pay 563 × $1.5 = $844.5

As for the mortar bags estimation, dividing 563 by 33.3 results in 16.9. As you are limited to buying whole bags, you should get 17 standard bags of mortar for this particular wall.

As with all construction projects, we advise that you buy at least 10% more material than you think needed in case of any unexpected mishaps. After all, it's better to be prepared beforehand rather than driving back and forth to the store and wasting time and gas.

If you need help calculating the right amount of additional materials, try using our percentage calculator.