Concrete Block Calculator — CMU Block, Mortar & Core Fill
Calculate CMU concrete blocks, mortar bags, core fill volume, horizontal reinforcement, bond beams, and lintel blocks for openings. Free online concrete masonry calculator.
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Block Sizes
6
Material Estimates
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Systems
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Enter your wall dimensions to estimate concrete block materials.
Blocks Needed
0 blocks
Mortar Bags (80 lb)
0 bags
Approximately 1 bag per 100 blocks
Core Fill Volume
0 cu yd
Horizontal Rebar
0 ft
Bond Beams
—
Lintel Blocks
—
Estimated Total Cost
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Wall Summary
Block Size8x8x16
Wall Area0 sq ft
Blocks0
Mortar0 bags
Core Fill0 cu yd
Total Cost—
Frequently Asked Questions
Calculate the wall area in square feet (length × height), subtract openings, then divide by the face area of one block. A standard 8x8x16 block covers 1.125 sq ft (16 in × 8 in = 128 sq in, divided by 144). Add 5–10% for waste and breakage.
Core fill (grout) is poured into the hollow cores of CMU blocks to add structural strength and reinforce the wall. The volume depends on the block size and whether all cores are filled. An 8x8x16 block has approximately 0.4 cubic feet of core volume when fully filled.
Bond beams are horizontal courses of specially shaped blocks (bond beam blocks) that are filled with grout and reinforced with horizontal rebar. They tie the wall together and distribute loads. Typically placed at the top of the wall, at floor levels, and at lintel height over openings.
8x8x16 blocks are the most common for standard walls. 6x8x16 blocks are used for non-load-bearing partitions or where space is limited. 10x8x16 and 12x8x16 blocks are used for thicker walls requiring more structural capacity or higher fire ratings.
Lintel blocks (also called header blocks) are U-shaped blocks placed over door and window openings to support the wall above. Estimate approximately 1 linear foot of lintel blocks per foot of opening width. For a 4-ft wide door, you need about 4 lintel blocks (each 16 inches long).