Concrete Block Calculator
Work out how many concrete blocks you need. A 40 x 6 ft wall needs about 284 standard 8x8x16 blocks including waste.
How many blocks per square foot
A standard 8 x 8 x 16 inch concrete block (CMU) covers 128 square inches of wall face, which is 0.889 sq ft once the mortar joint is counted. That is about 1.125 blocks per square foot of wall.
The 40 x 6 ft wall is 240 sq ft, so 284 blocks with 5% waste, plus 9 bags of mortar. Blocks and mortar cost about $747.00.
Plan for more than blocks
- Rebar and grout for filled cores in structural walls
- Footing concrete. Use the cubic yard calculator.
- Cap blocks and half blocks at ends
One 80 lb bag of mortar lays about 33 blocks, so allow 3 bags per 100 blocks.
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Frequently asked questions
How many concrete blocks do I need per square foot?
About 1.125 standard 8x8x16 blocks per square foot of wall.
How many blocks are in 100 square feet?
Around 113 blocks.
How much mortar do I need for 100 blocks?
About 3 bags of 80 lb mortar.
What size is a standard concrete block?
Nominal 8 x 8 x 16 inches. The actual size is 7 5/8 x 7 5/8 x 15 5/8 inches.
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