Cinder block fill calculator: how much concrete do I need to fill cinder blocks?
88 bags
of 80 lb grout · 57.8 cu ft, 2.14 cubic yards at 36.1 cu ft per 100 sq ft · for a 40 × 4 ft wall of 8 in block
Run your own numbers
Enter it the way you measured it: 4.5, 4 1/2,
3/8 or 10' 6".
88 bags
of 80 lb grout · 57.8 cu ft, 2.14 cubic yards at 36.1 cu ft per 100 sq ft
Source: Concrete Masonry & Hardscapes Association, TEK 04-02A Estimating Concrete Masonry Materials, Tables 3 and 4, read October 24, 2026. Read the source
Filling every cell of a 40 × 4 ft wall of 8 inch block takes 57.8 cubic feet of grout, 2.14 cubic yards or 88 bags of 80 lb, at 36.1 cu ft per 100 sq ft with 3% waste, by CMHA TEK 04-02A.
A worked example
A 27 ft 6 in wall, 6 ft 8 in high, of 12 inch block grouted every 32 in needs 42 bags of 80 lb. 183.3 sq ft of wall at 14.8 cu ft per 100 sq ft is 27.1 cu ft of grout, 1.01 cubic yards, or 41.1 bags of 0.66 cu ft rounded up to 42.
How many cinder block cores does an 80 lb bag fill?
About 2.7 cores of 8 in block, 3.6 of 6 in block, 2.2 of 10 in and 1.8 of 12 in, by CMHA TEK 04-02A Table 4: an 80 lb bag of preblended grout yields about 0.66 cu ft.
Can you fill 4 inch cinder block?
CMHA does not recommend grouting conventional 4 in units: the cells are too small to place and consolidate the grout well, which is why its Table 3 starts at 6 in block.
What else it is called
The cores of cinder block, concrete block or CMU are filled with masonry grout, the fluid mix the CMHA tables measure; filling every cell is solid grouting, filling some cells is partial grouting. Searched as a cinder block fill calculator, how much concrete to fill cinder blocks or block core fill calculator.
Grout per 100 sq ft of wall
| Grouted cells every | 6 in block | 8 in block | 10 in block | 12 in block | 14 in block |
|---|---|---|---|---|---|
| 8 in (every cell) | 25.6 | 36.1 | 47 | 58.9 | 74.5 |
| 16 in | 12.8 | 18.1 | 23.5 | 29.5 | 37.3 |
| 24 in | 8.6 | 12.1 | 15.7 | 19.7 | 24.8 |
| 32 in | 6.4 | 9.1 | 11.8 | 14.8 | 18.6 |
| 40 in | 5.2 | 7.3 | 9.4 | 11.8 | 14.9 |
| 48 in | 4.3 | 6.1 | 7.9 | 9.9 | 12.4 |
| 56 in | 3.7 | 5.2 | 6.8 | 8.5 | 10.6 |
| 64 in | 3.2 | 4.6 | 5.9 | 7.4 | 9.3 |
| 72 in | 2.9 | 4.1 | 5.3 | 6.6 | 8.3 |
| 80 in | 2.6 | 3.7 | 4.7 | 5.9 | 7.5 |
| 88 in | 2.4 | 3.3 | 4.3 | 5.4 | 6.8 |
| 96 in | 2.2 | 3.1 | 4 | 5 | 6.2 |
| 104 in | 2 | 2.8 | 3.7 | 4.6 | 5.7 |
| 112 in | 1.9 | 2.6 | 3.4 | 4.3 | 5.3 |
| 120 in | 1.8 | 2.5 | 3.2 | 4 | 4.9 |
Cubic feet of grout per 100 square feet of hollow single wythe wall, two-core units, 3% waste included: CMHA TEK 04-02A Table 3. An 80 lb bag of preblended grout yields about 0.66 cu ft (Table 4).
Where the numbers come from
- Grout per 100 sq ft of wall: CMHA TEK 04-02A, Table 3 «Grout Volume Estimation for Hollow Single Wythe Concrete Masonry Walls», cubic feet by grout spacing (8 to 120 in) and wall width (6 to 14 in), assuming «two-core hollow concrete masonry units and 3% waste»; walls of 4 in units are not included because CMHA does not recommend grouting them. Read October 24, 2026. CMHA TEK 04-02A
- Bags: CMHA TEK 04-02A, Table 4, an «80 lb (36.3 kg) bag yields approximately 0.66 ft3» of preblended grout and fills about 3.6, 2.7, 2.2 and 1.8 cores of 6, 8, 10 and 12 in block. Read October 24, 2026. TEK 04-02A Table 4
- The rest is arithmetic: cu ft = wall sq ft ÷ 100 × the Table 3 value; cubic yards = cu ft ÷ 27; bags = cu ft ÷ 0.66, rounded up.
Table 3 fills the vertical cells of hollow two-core units in a single wythe wall. Grouting a course horizontally, as in a bond beam, takes more grout on top of this.
By Javier Miralles · Last updated . How this site is made.
Other materials
Embed this calculator
Free to use on your own site. Copy the code and keep the credit line.