Block Fill Calculator

Enter the wall size, block width and which cells are grouted and get the grout in cubic feet and yards and the bags of preblended grout, from the CMHA (NCMA) estimating tables.

Construction & DIYUnited States onlySource: CMHA TEK 04-02A grout volume tablesFree, no sign-up

Wall length (ft)

Wall height (ft)

Openings (ft²)

Block width

Which cells are grouted

Hollow single-wythe walls of two-core block. The result updates as you type.

Grout to fill the cores

115.5 ft³ · 4.28 cubic yards

176 bags of 80 lb preblended grout (or 5 × 3,000 lb) · about 381 blocks (8 × 16) in 320 ft² of wall

Grout per 100 ft² (TEK 04-02A Table 3, incl. 3% waste)	36.1 ft³
Wall area	320 ft²
80 lb preblended bags (≈0.66 ft³ each)	176
Cores one 80 lb bag fills (Table 4)	2.7 cores of 8 in block
Blocks at 119 per 100 ft² (incl. 5% waste)	381

What this page cannot tell you

Which cells must be grouted or reinforced — that's set by the wall's design and your building code. Absorbent block, pumping versus bucketing, and bond beams change grout use; TEK 04-02A notes horizontal bond-beam grouting is extra and that 4 in units aren't covered.

How to calculate grout for block cores

Measure the wall. Length and height in feet; subtract openings.
Pick the block width. 6, 8, 10, 12 or 14 in.
Choose the grout spacing. Every cell (solid), or cells at 16, 24, 32, 48 in or more on centre.
Read the grout. Cubic feet, cubic yards and preblended bags.

10 situations where a block fill calculator helps

Ordering grout for a retaining wall

Solid-grouted walls take a lot; get the yards for a truck order.

Partially grouted walls

Cells at 32 or 48 in on centre need far less.

Bags or ready-mix

Compare preblended bag counts with a delivered load.

Foundation walls

Grout volume for reinforced cells.

Pricing a block wall

Blocks and grout in one estimate.

Garden walls and planters

Small walls in bags.

Comparing block widths

An 8 in wall takes about 40% more grout than a 6 in wall.

Checking a contractor's quote

Compare their grout quantity.

Pump or bucket

Know the volume before deciding how to place it.

Block count

About 119 8 × 16 blocks per 100 ft², waste included.

Where the figures come from

The grout volumes are Table 3 of TEK 04-02A, 'Estimating Concrete Masonry Materials', from the Concrete Masonry & Hardscapes Association (CMHA, formed from NCMA and ICPI): cubic feet of grout per 100 ft² of hollow single-wythe wall, by wall width (6, 8, 10, 12 and 14 in) and grout spacing from 8 in (every cell) to 120 in. The table 'assumes two-core hollow concrete masonry units and 3% waste'. For example, an 8 in wall grouted solid takes 36.1 ft³ per 100 ft².

Bags use TEK 04-02A Table 4's note that an 80 lb bag of preblended grout yields approximately 0.66 ft³ (a 3,000 lb bulk bag about 25 ft³); the table also lists how many cores one bag fills. The block count uses the TEK's 119 units per 100 ft² (8 × 16 units, 5% waste included).

Limits: TEK 04-02A says walls of 4 in units are not included and it does not recommend grouting them. Bond beams (horizontal grouting) need extra grout. Which cells must be grouted and reinforced is set by the design and your code. Absorbent block and the placing method change real use. Everything runs in your browser.

Sources

CMHA — TEK 04-02A Estimating Concrete Masonry Materials — Table 3 grout volumes; Table 4 bag yields

Frequently asked questions

How much grout to fill 8 inch block?

36.1 ft³ per 100 ft² of wall when every cell is filled, per TEK 04-02A — about 1.34 cubic yards.

How many bags of grout per block?

TEK 04-02A Table 4: one 80 lb bag fills about 2.7 cores of 8 in block.

How do I calculate grout for partially grouted walls?

Pick the spacing of the grouted cells; the table gives the volume for that spacing.

Does it include waste?

Table 3 includes 3% waste; add more if you expect losses.

Can I grout 4 inch block?

TEK 04-02A doesn't include it and doesn't recommend grouting 4 in units.

Does it include bond beams?

No — horizontal grouting is extra.