Free Concrete Block Calculator
Calculate how many concrete blocks (CMU) you need for a wall. Enter wall dimensions and block size to get the number of blocks required.
Standard CMU is 16 inches including mortar joint
Standard CMU is 8 inches including mortar joint
Blocks (with waste)
284
Blocks (with waste) vs Wall Length
How to Calculate Concrete Blocks Needed
Formula
Blocks = Wall Area / Block Face Area
A standard CMU (Concrete Masonry Unit) is 8 in x 8 in x 16 in nominal (including mortar). The face area of one block with mortar is (16/12) x (8/12) = 0.889 sq ft. So roughly 1.125 blocks per square foot of wall. Always add 5-10% for breakage and cuts.
Example Calculation
A block wall 30 ft long and 8 ft high using standard 8x8x16 blocks with 5% waste.
- 01Wall area = 30 × 8 = 240 sq ft
- 02Block face area = (16/12) × (8/12) = 1.333 × 0.667 = 0.889 sq ft
- 03Blocks needed = 240 / 0.889 = 270 blocks
- 04With 5% waste = 270 × 1.05 = 284 blocks
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