# How to Calculate How Many Concrete Blocks are Needed for a Garage

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If you can do simple math, you can estimate concrete block needs.
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If you are planning to build a garage out of concrete block, you should know how many blocks you will need before you shop around at local block suppliers. Fortunately, a concrete block is standardized, with a face 8 inches high by 16 inches long, so you can use simple math to estimate the number of blocks your garage project will require.

## Step 1

Find the perimeter of your planned garage by adding together the planned length of all four walls in feet. Subtract from that figure the width in feet of the garage door or doors since you are not going to put a wall in the door opening. For instance, if your garage will be 24 feet wide by 20 feet deep, with two 9-foot-wide doors, you add 24 + 24 + 20 + 20 to get 88 feet, then subtract 18 feet for the doors to get a 70 foot net perimeter.

## Step 2

Multiply the net perimeter by the planned height in feet to get the total wall area in square feet. If your garage walls are to be 10 feet tall, multiply 10 by the 70-foot net perimeter to get 700 square feet of total wall area. For this rough estimate, you don't need to deduct side door or side window area.