Blocks to buy
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CMU wall material estimator
Concrete Block Calculator
Estimate concrete block or CMU counts from wall length, height, block face size, openings, waste allowance, and price per block. Built for quick foundation, garden wall, and partition takeoffs.
Units
Net wall area
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Base blocks
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Estimated block cost
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CMU count is not structural design
Confirm wall thickness, bond pattern, corners, pilasters, lintels, grout cells, rebar, footing, code, and engineered details before building. This calculator estimates face-block quantity only.
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Concrete Calculator
Estimate footing or filled-cell concrete volume after sizing the block wall.
RelatedRebar Calculator
Plan slab or footing reinforcement separately from CMU block count.
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Estimate face-brick counts, mortar-joint spacing, waste, and brick cost for masonry walls.
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Concrete Block Calculator formula
Gross wall area = wall length × wall height
Net wall area = max(gross area - openings, 0)
Block face area ft² = (block length in × block height in) ÷ 144
Base blocks = net wall area ÷ block face area
Blocks to buy = ceil(base blocks × (1 + waste %))
Example
A 32 ft by 8 ft wall with 24 sq ft of openings has 232 sq ft net area. Standard 16×8 in blocks cover 0.89 sq ft each, so base count is about 261 blocks. With 8% waste, buy 282 blocks.
Concrete Block Calculator FAQ
How many concrete blocks are in a square foot?+
A standard 16 in by 8 in block face covers about 0.89 square feet, so a simple wall uses roughly 1.125 blocks per square foot before waste.
Does this include mortar?+
No. This page estimates block count and block cost only. Mortar, grout, rebar, bond beams, lintels, and footings should be estimated separately.
Should I subtract doors and windows?+
Yes. Enter the total opening area to subtract, then keep enough waste for cuts around those openings.
What waste should I use for CMU?+
Use about 5% for a clean rectangular wall and 8-12% when there are corners, openings, cuts, breakage, or limited supplier access.