🧱 Concrete Block Calculator
Calculate how many standard concrete blocks (CMUs) you need to build a wall.
ft
ft
in
in
%
What this calculator does
This tool estimates how many concrete masonry units (CMUs, commonly called cinder blocks) you need to build a wall of a given length and height, accounting for the block face size including the mortar joint.
The formula
Blocks needed = wall area ÷ block face area (block length × block height, converted to square feet), rounded up and increased by a waste percentage to cover cuts and breakage. The standard US block face is nominally 16 in × 8 in.
This estimate does not account for corners, openings, or special block types (half blocks, bond beams). Adjust for openings and consult a mason for structural wall designs.
Last reviewed August 2026