Concrete Block Calculator

Determine exact 8×8×16 CMU block counts, Type S mortar bags, and core grout fill for structural masonry walls.

Wall Length (Feet)

Wall Height (Feet) 8" per course (0.667 ft)

Block Size Standard

Core Fill Grouting

Door & Window Openings (Sq Ft to Deduct) e.g. 3x7 ft exterior door = 21 sq ft

Total CMU Blocks to Order

272 Blocks

12 Courses High (Includes 5% Waste)

Type S Mortar Bags 9 Bags 80 lb pre-mixed bags

Core Grout Concrete 1.1 Cu Yd Pourable masonry grout

Standard Block Factor: 1.125 Blocks / Sq Ft A standard 8×8×16 block with 3/8" mortar joint has a nominal face area of 8" × 16" (128 sq inches = 0.888 sq ft). Exactly 112.5 blocks cover 100 square feet of wall.

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How Concrete Masonry Unit (CMU) Quantities Work

Standard architectural cinder blocks are manufactured 3/8" smaller than nominal dimensions (7-5/8" high by 15-5/8" long). When laid with standard 3/8" bed and head mortar joints, each block occupies exactly 8 inches in height by 16 inches in length.

Wall Area = (Length × Height) - Openings
Blocks = Wall Area × 1.125 × 1.05 (5% cutting waste)
Mortar = 1 eighty-pound bag per 30 to 35 standard CMU blocks

Frequently Asked Questions

How many concrete blocks are on a standard pallet?

A standard wooden pallet holds 90 to 108 units of 8x8x16 concrete blocks, weighing roughly 3,200 to 3,800 lbs.

What type of mortar is required for block foundation walls?

Type S mortar (minimum 1,800 PSI compressive strength) is code-mandated for below-grade foundation walls, retaining walls, and seismic zones requiring high lateral bond strength.

How much grout fills 100 concrete blocks?

Filling all cores of 100 standard 8" CMU blocks requires approximately 0.90 to 1.0 cubic yard of fine concrete masonry grout.