Estimate how many concrete blocks and mortar bags a wall needs.
Estimate only, based on 1.125 standard blocks per sq ft, ~3 bags of Type S mortar per 100 blocks (3/8" joints), and ~0.15 cu ft of grout per fully-filled core (80 lb bag ≈ 0.6 cu ft yield). Actual coverage varies by block manufacturer, joint thickness, and rebar/grout spec — confirm with your supplier or engineer for structural or large orders.
| Wall | Date | Dimensions | Net Area | Blocks | Mortar Bags | Grout Bags | |
|---|---|---|---|---|---|---|---|
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Standard CMU blocks have a nominal face of 16" × 8", which works out to 1.125 blocks per square foot of wall — a widely used estimating shortcut in masonry. Net wall area (gross area minus door/window openings) multiplied by that ratio, then bumped up for waste, gives the block count.
Mortar coverage depends on joint thickness and block size, but a common rule of thumb for standard 3/8" joints is about 3 bags of Type S mortar mix per 100 blocks. This calculator uses that ratio — for a precise order on a large job, your block supplier can typically give a more exact figure based on their specific product.
For reinforced walls, vertical rebar is typically "set" in place by filling specific cores with grout. A standard 8" CMU core holds roughly 0.15 cubic feet of grout when fully filled. Entering the percentage of cores being grouted estimates the grout bag count (based on an 80 lb bag yielding about 0.6 cubic feet) — but core spacing and rebar schedules are structural decisions your engineer or local code should specify, not something this calculator determines for you.