Block Fill Calculator
Estimate grout to fill CMU block cores.
Block fill (grout) volume depends on core size: an 8 inch CMU holds about 0.5 cu ft of grout per block when fully filled, a 12 inch block about 0.9 cu ft. Multiply the number of filled cells by that volume, divide by 27 for cubic yards, and add 5–10% waste. Enter your wall size for yards and bag counts.
How does the block fill calculator work?
A standard 8×8×16 CMU has ~0.087 ft³ of core volume (both cells). Multiply block count by core volume by the percentage of cells you're filling to get total grout volume.
Which guide explains this in more depth?
- How inspectors check brick and mortar counts on a single-wythe wall. Read the inspector-approved brick calculator method guide for the full worked example.
What else do people ask about this calculator?
How much grout for a CMU wall?
Fully grouted 8 in CMU takes about 1 yd³ per ~310 blocks. Partially grouted (every other cell) roughly halves that.
What mix is used for block fill?
Fine-aggregate grout with 8–11 in slump, ~2000–3000 psi. Sold pre-bagged as 'core fill grout' or 'block fill'.
Which related calculators should I use next?
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