CMU Block Wall Takeoff Calculator: Blocks, Mortar and Grout

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Field note: this tool runs entirely in your browser. Load the page before you head out and it keeps working with no signal, and Print or save PDF gives you a clean copy for the truck.

CMU Block Wall Takeoff Calculator: Blocks, Mortar and Grout

Wall dimensions to a full masonry order: blocks with waste, mortar bags, grout volume from your reinforcing layout, bars and joint reinforcement, with a course count cross check.

Bill of materials

Based on standard 8 by 8 by 16 nominal block, 1.125 blocks per square foot of wall face. Grout per cell and blocks per bag are editable because they vary by block type and mortar product; check your supplier sheet. Structural design of the wall is a separate exercise.

Diagram of a running bond CMU wall showing grouted cells with vertical bars at a set spacing
Running bond block wall with grouted, reinforced cells at the chosen spacing. The takeoff counts blocks, mortar, grout and steel.

Counting a block wall the way it gets built

A CMU takeoff is mostly geometry with a few supplier numbers on top. Standard 8 by 8 by 16 nominal block shows a 16 by 8 in face, which is 0.888 ft^2, so every square foot of wall face needs 1.125 blocks. Net the openings out of the gross area, add waste for cuts and breakage, and the block count falls out. The tool also lays the wall out in courses so you can sanity check the count against how it will actually stack.

A worked example with a built in cross check

A 40 ft wall 8 ft tall with no openings has 320 ft^2 of face, which is 360 blocks before waste and 378 at five percent. Here is the satisfying part: that same wall stacks as 30 blocks per course, since each block is 16 in long, across 12 courses of 8 in each. Thirty times twelve is 360, exactly the area count. When the two routes to the number agree, the takeoff is probably right.

Grouted cells follow the reinforcing layout. At 48 in spacing along 40 ft you get 11 vertical cell columns. At 0.2 ft^3 of grout per vertical foot of cell, those columns plus one bond beam course come to about 1.24 yd^3 of grout, with 88 lf of vertical bar and 40 lf of bond beam bar. Joint reinforcement every second course adds 6 rows, 240 lf of ladder wire.

The numbers you should edit

Two defaults deserve your attention rather than blind trust. Grout volume per cell varies with the block core shape, so check your block supplier data and adjust. Mortar coverage varies by product and joint thickness; 28 blocks per bag of premix is a common planning figure but your bag will say otherwise if it disagrees. Both fields are editable precisely because pretending one number fits every product is how takeoffs go wrong. And none of this is structural design: bar sizes, spacing and grouting requirements come from the design, not the takeoff.

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