This concrete block calculator finds how many concrete blocks (CMUs) you need to cover a given wall area. Enter the area and block face size above for the count plus a waste allowance.
Formula
Blocks = Wall area ÷ Block face area × (1 + waste %)
A standard 16″ × 8″ block covers about 0.89 ft², or roughly 1.125 blocks per ft².
Example
160 ft² wall: 160 × 1.125 = 180 blocks, plus 5% = 189 blocks.
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Frequently Asked Questions
How many concrete blocks do I need?
Divide the wall area by the block face area, or multiply square footage by 1.125 for standard 16×8 blocks, then add waste.
What is the size of a standard concrete block?
Nominally 16 inches long by 8 inches high, giving a face area of about 0.89 square feet including the mortar joint.
How much waste should I add?
About 5 percent for breakage and cuts, rounding up to whole blocks.