Concrete Block Calculator

How many standard 8×8×16 blocks a wall needs. Enter the wall size, take out doors and windows, and add a little for breakage.

How the count works

A standard block is 7⅝ × 7⅝ × 15⅝ in. With a ⅜ in mortar joint it fills a nominal 8 × 16 in, which is 0.889 sq ft of wall face. That works out to 1.125 blocks per square foot.

Blocks = (length × height − openings) × 1.125 × (1 + waste)

Example: a 30 ft wall that is 6 ft high is 180 sq ft. That takes 203 blocks: 9 courses of 23 blocks each.

Corners, ends and openings need half blocks or corner blocks. Count them separately once the layout is drawn, and order a few spare. Blocks crack in transport and when cut.