Concrete Block Calculator
Standard 8×8×16 CMU: blocks with waste, plus the mortar.
Common questions
How many concrete blocks per square foot?
1.125 — a standard 8×8×16 block covers 0.89 sq ft of wall with its mortar joints. The calculator adds 10% for cuts and corners.
How much mortar for block work?
Three 80 lb bags of mortar per 100 blocks is the estimating standard — block work uses less mortar per square foot than brick because the units are so much bigger.
Do block walls need to be filled?
Structural walls typically get rebar and grout (concrete fill) in cores at corners, ends, and every 32–48" — your plans or local code specify. Figure grout fill at about 0.25 cu ft per filled core for 8" block.