Concrete Block Calculator

About 1.13 blocks per square foot for any standard CMU with a 3/8 in mortar joint. The actual 7.625 by 15.625 in block plus mortar forms an 8 by 16 in nominal module, so the face count is identical regardless of width.

No, not for face count. Width (4, 6, 8, or 12 in) affects wall thickness and load capacity but not the face. The calculator returns the same block count for all four sizes.

For a standard 3/8 in joint, the calculator estimates 8.5 cubic feet of wet mortar per 100 square feet with a 10% waste factor. Changing the joint thickness or waste factor adjusts that estimate. It rounds up from published coverages of up to 13 standard 8 x 8 x 16 in blocks per 80 lb bag and 9 blocks per 60 lb bag. Check the product label before ordering.

10% is a safe default for a typical residential wall with one or two openings. Drop to 5% for a long straight run with no cuts, and go up to 15% for walls with many corners, angled cuts, or partial blocks.

The calculator estimates corner blocks at about 5% of total block count, which covers a typical rectangular wall. For more returns or pilasters, count corners directly (one block per course per corner).