Block-Core Grout Fill Calculator
Short answer: a 20 × 8 ft wall of 8-inch blocks, fully grouted, needs 48.6 cu ft of grout — 1.80 cubic yards (75 × 80 lb bags of coarse core-fill grout). Enter your wall below.
Calculate your grout fill
How the calculation works
Method A (primary): blocks × grout per block. Block count comes from the wall area and the 8 × 16 in block face (8/9 sq ft per block, two cores per block — CMHA TEK 04-02A). For partial grouting, grouted cores are counted as core columns at the spacing you enter, times the number of courses, and each core holds half the per-block figure. Method B (cross-check): the CMHA table of grout per 100 sq ft of wall, which already includes 3% waste. The two methods are shown side by side and never averaged — at 8 inches they differ by about 19%, which is a real difference between published sources, not a rounding error.
Worked example: 20 × 8 ft wall, 8-in regular blocks, fully grouted → 160 sq ft; 180 blocks net; 180 × 0.27 = 48.6 cu ft = 1.80 cubic yards; bags: 75 coarse, 72 fine, 74 generic (80 lb). Method B cross-check: 57.76 cu ft = 2.14 cubic yards → 89 coarse bags.
Published grout figures used on this page
| Block (Amcon / TCC Block Manual 2018, core-filling data) | Grout per block |
|---|---|
| 6-in regular | 0.22 cu ft |
| 8-in regular | 0.27 cu ft |
| 8-in, 3-hour rated | 0.18 cu ft |
| 8-in bond beam | 0.23 cu ft |
| 10-in regular | 0.325 cu ft |
| 12-in regular | 0.47 cu ft |
| CMHA table (cu ft per 100 sq ft, includes 3% waste) | Full grouting |
|---|---|
| 6-in | 25.6 |
| 8-in | 36.1 |
| 10-in | 47.0 |
| 12-in | 58.9 |
| 14-in | 74.5 |
8-in partial grouting by spacing (CMHA, cu ft per 100 sq ft): 8 in → 36.1; 16 in → 18.1; 24 in → 12.1; 32 in → 9.1; 40 in → 7.3; 48 in → 6.1; 96 in → 3.1; 120 in → 2.5.
| 80 lb bag yield (approximate) | Cu ft per bag |
|---|---|
| QUIKRETE Core-Fill Grout, coarse | 0.65 |
| QUIKRETE Core-Fill Grout, fine | 0.68 |
| QUIKRETE Core-Fill Grout, self-consolidating | 0.65 |
| CMHA generic core-fill grout | 0.66 |
Bag counts are volume ÷ yield, rounded up. The “3 blocks per bag” shortcut found on some sites is not used here.
How to use this calculator
- Enter your measurements in the calculator above, in the units shown.
- Check the inputs against what you measured — depth is the number most often entered wrong.
- Press Calculate, then use the order amount (with waste, where shown) when you buy or order.
Frequently asked questions
How much grout do I need to fill block cores?
It depends on the wall, the block width and the grouting method: a 20 × 8 ft wall of 8-inch blocks, fully grouted, needs 48.6 cu ft of grout — 1.80 cubic yards, or 75 × 80 lb bags of coarse core-fill grout.
Why do the two methods on this page give different answers?
They come from different published sources with different assumptions, including absorption and delivery losses. At 8 inches they differ by about 19%. The difference is real, not a rounding error, so the two figures are shown side by side and never averaged.
What is partial grouting?
Partial grouting fills only the reinforced cells, at a spacing set by the structural design, instead of every core. Which cores are grouted is a structural decision, not a quantity choice.
Can I grout 4-inch blocks?
No. The Concrete Masonry and Hardscapes Association states that 4-inch units should not be grouted, so 4-inch blocks are not offered on this calculator.