Masonry Grout Calculator
Cubic yards and bags of grout to fill CMU cores — sized by wall area, block size, and how many cells you're grouting.
grout = 90 × 0.3 cu ft = 27 cu ft (1 cu yd) → +5% = 1.1 cu yd
Masonry grout is the fluid concrete pumped into the hollow cores of a block wall to bond the reinforcing steel and add strength. It is not the same as mortar, which goes in the joints between blocks. This calculator sizes grout, so it works from how many cores you are filling rather than the joints.
Start with the wall area, which gives a block count at the usual 1.125 blocks per square foot. Each block has two cores, and how many you fill depends on the design: a fully grouted wall fills every cell, while a reinforced wall might grout only every other cell, or every third or fourth. The calculator multiplies the block count by the grouted fraction, then by the grout volume of one block's cores for your block size — about 0.30 cubic feet for a standard 8-inch block, more for wider units.
The result is given as cubic yards to order — the way ready-mix grout is delivered — plus a bag count if you are mixing grout on site. Because core volume varies with the block manufacturer and how full the pour gets, treat the number as a solid estimate and confirm against your block's published core volume for large jobs.
grouted cells = 80 × 1.125 = 90 · grout = 90 × 0.30 cu ft = 27 cu ft = 1.0 cu yd
order (+5%) ≈ 1.1 cu yd → 48 × 80 lb bags