CMU Grout Fill Calculator: Core Fill for Concrete Block Walls

1. Set Wall size by to length x height and enter the wall length and height in feet, or switch to Area and type the wall area. Subtract any openings.
2. Choose the block width (6 to 14 in) and the vertical grout spacing (solid, or 16 to 48 in on center). These two pick the exact CMHA Table 3 figure.
3. Pick the grout product to load its bag yield, add any bond-beam length, and read the bags and cubic yards. Switch "Show mainly" to see cubic yards up front.

A CMU grout fill calculator estimates how much grout fills the hollow cores of a concrete masonry unit (CMU) wall. It turns wall area, block width and grout spacing into cubic feet, then into 80 lb bags or cubic yards.

This is a volume-fill problem, not a joint-fill problem. It measures the grout poured inside the block cores and bond beams, not the thin mortar joints between blocks. For tile grout in joints, use the grout calculator instead; filling block cores, you are in the right place.

Grout is the fluid concrete mix pumped or poured into reinforced cells to bond the steel and the block into a structural wall. The amount depends on how many cells are filled, which the engineer sets through the reinforcement spacing.

The calculator reads one figure from CMHA TEK 04-02A Table 3, the cubic feet of grout per 100 square feet of wall for your block width and grout spacing, then scales it to your wall.

Table 3 is built for two-core hollow units and already includes a 3 percent waste allowance. Wider grout spacing fills fewer cores, so the figure drops: filling every core (solid) in an 8 in wall uses 36.1 cu ft per 100 sq ft, while 16 in on center uses 18.1, almost exactly half.

1. Wall area. Length times height, in square feet, minus any openings you subtract.
2. Table 3 figure. The calculator looks up the cell for your width and spacing. 4 in units are excluded, since CMHA does not recommend grouting them.
3. Volume. Area divided by 100, times that figure, gives cubic feet of core fill. Bond beams are added from Table 5.
4. Bags and yards. Divide by the bag yield and round up for bags, or divide by 27 for cubic yards.

Sakrete does not publish a comparable per-bag core-fill yield, so choose Custom and enter the yield from the bag you buy.

Take a 400 sq ft wall of 8 in block, grouted at 16 in on center, filled with Quikrete Core-Fill Fine in 80 lb bags.

1. Table 3 figure: an 8 in wall at 16 in on center is 18.1 cu ft per 100 sq ft.
2. Core-fill volume: 400 / 100 x 18.1 = 72.4 cu ft, waste already included.
3. Bags: 72.4 / 0.68 = 106.47, so buy 107 bags of 80 lb Fine grout.
4. Cubic yards: 72.4 / 27 = 2.68 cu yd if you order ready-mix instead.

At 2.68 cu yd this job sits near the line where ready-mix grout starts to beat bags on price and labor. The calculator flags that in the verdict band.

Four inputs move the answer, and grout spacing moves it most.

Vertical Grout Spacing

This is the biggest lever. Going from solid fill to 48 in on center cuts an 8 in wall from 36.1 to 6.1 cu ft per 100 sq ft, about one sixth the grout. The engineer sets this through the rebar spacing; see the rebar spacing and quantity calculator.

Block Width

Wider block has bigger cores. A 14 in wall holds nearly three times the grout of a 6 in wall at the same spacing, because each cell is deeper.

Wall Area and Openings

Grout scales straight with net area. Subtracting doors and windows matters on walls with large openings.

Bond Beams

Horizontal bond-beam courses add grout on top of the vertical cores. They are counted separately here from CMHA Table 5.

Bags win on small jobs; ready-mix wins once the volume climbs past roughly one cubic yard.

As a rough cost basis, a per-100-blocks figure is sometimes quoted. It is not a published constant, so derive it: at 3 blocks per 0.68 cu ft Quikrete bag that is about 0.84 cu yd per 100 blocks, while CMHA solid-fill math gives about 1.19 cu yd per 100 blocks. The gap is why this tool estimates from wall area and Table 3, not from a block count. For the wall concrete itself, see the concrete calculator.

Ordering Grout for a Reinforced Block Wall

Enter the wall, pick the width and the engineer's grout spacing, and read the bags or cubic yards to order.

Choosing Bags or Ready-mix

Switch "Show mainly" to cubic yards. If it crosses about one cubic yard, price a ready-mix delivery against bags.

Checking a Supplier Quote

Run the same wall here. A big gap usually means a different grout spacing or block width than the quote assumed.

Adding Bond Beams

Enter the linear feet of bond-beam courses to fold their grout into the total, shown separately for clarity.

1. Grouting Every Core by Habit

Most reinforced walls are partially grouted at a set spacing, not solid. Using solid fill when the spec says 32 in on center can nearly double the order.

2. Forgetting the Block Width Changes the Cell Size

Wider block holds more grout per core. Always match the width to the actual units.

3. Trying to Grout 4 in Units

CMHA does not recommend grouting 4 in block, and Table 3 excludes it. The calculator blocks that choice.

4. Ignoring the Waste Allowance

Table 3 already includes 3 percent waste. Adding another large allowance on top double-counts it; see the material waste guide for how allowances work.

5. Mixing Up Bond Beams and Vertical Cores

Bond beams are horizontal and use Table 5. Counting them as extra vertical cores overstates the grout.

6. Rounding Bags Down

Bags are sold whole. 106.5 bags means 107. Running short mid-pour risks a cold joint in the grout.

The calculator reproduces CMHA Table 3 exactly and converts to bags and cubic yards with verified bag yields. Real pours vary with workmanship and block tolerances.

Table 3 assumes two-core hollow units. Special-shape, three-core or open-end units can differ. Always confirm the quantity against your engineer's spec and the current product data sheet.

It depends on wall area, block width and grout spacing. For a 400 sq ft wall of 8 in block grouted at 16 in on center, CMHA Table 3 gives 72.4 cu ft, about 107 bags or 2.68 cu yd. Solid fill would use roughly twice that.

About 3 standard 8 x 8 x 16 in blocks per 80 lb bag, per Quikrete Core-Fill Grout Fine and Coarse data sheets. Each bag yields roughly 0.65 to 0.68 cu ft of grout.

Grout in cubic feet equals wall area divided by 100, times the CMHA Table 3 figure for your block width and grout spacing. That figure already includes a 3 percent waste allowance.

For solid fill, read the 8 in on center row of Table 3: 25.6 cu ft per 100 sq ft for 6 in block, 36.1 for 8 in, 47.0 for 10 in, 58.9 for 12 in and 74.5 for 14 in. Multiply by your area over 100.

No. CMHA does not recommend grouting 4 in units and Table 3 excludes them, because the cores are too small to place and consolidate grout reliably. Use 6 in or wider for grouted, reinforced walls.

Once the volume passes about one cubic yard, ready-mix delivered by the cubic yard is usually cheaper and faster than mixing bags. Switch the calculator to cubic yards to see where your job lands.

Enter the total linear feet of horizontal bond-beam courses. The calculator uses CMHA Table 5 (2.7, 2.0 and 1.6 linear feet per 80 lb bag for 6, 8 and 12 in block) and shows the bond-beam grout separately.

No. That figure appears only on aggregator sites, not on any CMHA or manufacturer document, and it does not match either basis. Quikrete bag math gives about 0.84 cu yd per 100 blocks and CMHA solid-fill math about 1.19, so this tool estimates from wall area and Table 3 instead.

Fine grout uses fine aggregate and yields about 0.68 cu ft per 80 lb bag; coarse adds larger aggregate and yields about 0.65. Coarse suits larger cores and lifts; follow the engineer's grout type and the data sheet.

No. The calculation runs in your browser and nothing is sent to our servers. Anything you choose to Save stays in this browser only.

• CMHA TEK 04-02A, Estimating Concrete Masonry Materials (Table 3 grout volume, Tables 4 and 5 yields) (Concrete Masonry and Hardscapes Association, read 2026-10-04).
• Quikrete Core-Fill Grout - Fine (No. 1585-08) data sheet: 0.68 cu ft per 80 lb bag (Quikrete, revised November 2024, read 2026-10-04).
• Quikrete Core-Fill Grout - Coarse (No. 1585-07) data sheet: 0.65 cu ft per 80 lb bag (Quikrete, revised November 2024, read 2026-10-04).