Concrete Block Calculator
Find out how many concrete blocks (CMUs) a wall needs. Enter the wall length and height — the calculator uses the standard 16 × 8 in block face and adds a waste allowance.
How it works
A standard concrete block has a 16 × 8 in face = 0.889 sq ft, so it takes about 1.125 blocks per square foot of wall. Blocks = wall length × height × 1.125, rounded up, plus your waste allowance.
Frequently asked questions
How many concrete blocks per square foot?
With a standard 16 × 8 in block, you need about 1.125 blocks per square foot of wall face.
Does this include mortar?
The 1.125 blocks/sq ft figure already assumes standard 3/8 in mortar joints. For mortar volume, plan on roughly 3 bags of mortar per 100 blocks.
What size is a standard concrete block?
A standard CMU is nominally 16 in long × 8 in high × 8 in wide (15⅝ × 7⅝ actual), giving a 16 × 8 in face for coverage math.
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Estimates are for planning only. Material yields, densities and code requirements vary — confirm quantities with your supplier and local building code before ordering.