How this calculator works
Divide net wall area by the nominal block face module, which includes a mortar joint. Subtract door and window areas before using known-area mode. Round the block purchase up after adding breakage and cutting waste. Mortar uses the blocks actually laid, excluding spare blocks. The initial coverage is the QUIKRETE Mason Mix estimate for standard 8 x 8 x 16 in units; change it for other units and bedding patterns. Block cost excludes mortar, reinforcement and labour.
Formula
Block equivalent = net wall area / (installed block length x installed course height); purchased blocks = ceil(block equivalent x (1 + waste)); mortar bags = ceil(block equivalent / blocks per bag).
Worked example
A 10 m2 wall using a 0.4 x 0.2 m installed module needs 125 block equivalents. Without waste, order 125 blocks and ten mortar bags at 13 blocks per bag. At $2 per block, the block purchase is $250.
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Frequently asked questions
Do I enter actual or nominal block dimensions?
Enter the installed module including one joint. For a typical nominal 16 x 8 in face, actual dimensions are smaller so the mortar joint completes the module.
Does this lay out each course?
No. Bond, corners, openings, lintels and cut units affect the actual order. Check a course layout before buying special units.
Why can mortar coverage vary?
Joint thickness, face-shell or full bedding, waste and block geometry change consumption. Use the product coverage for the wall being built.