CMU core fill and grout estimator

Concrete Block Fill Calculator

This concrete block fill calculator estimates CMU and cinder block core fill from wall size, block count, or filled cores. Get grout volume plus 60-lb and 80-lb bag totals.

Estimate block core fill

Start with

Unit:

Wall dimensions

Wall Length (ft)

Wall Height (ft)

Order Volume

1.98 cu yd

80-lb Bags

60-lb Bags

119

Block, fill, waste, and product settings

Block Size

Core Fill Scope

Waste Allowance10%

Use the allowance that matches your project conditions.

Product Bag Yield

Use the mixed-volume yield printed on the product bag. Changing yield affects bag totals only.

80-lb bag yield (cu ft)

60-lb bag yield (cu ft)

Estimate grout allowance and wall budget

Every cell

Which CMU cores are included?

All 12 example cores are included in this planning estimate.

Use the fill pattern specified by your structural drawings. If you know the actual quantity, use Filled cores instead of a spacing estimate.

Example only: standard two-core CMU shown. Bond beams and nonstandard block shapes are not included.

This visual explains grout-volume scope only. It does not specify rebar or structural design.

For 3-web, 4-web, architectural, or other nonstandard CMU, use the manufacturer's core-volume table.

Bond beams, lintels, footings, slabs, and solid walls are not included.

How the grout estimate is calculated

Method reviewed July 2026

The calculator uses the nominal 16 by 8 inch face of standard CMU, supplier blocks-per-cubic-yard benchmarks, the selected fill pattern, and your waste allowance. The result is a purchasing estimate, not a structural design.

Formula chain

1Standard blocks = ceiling(wall area ÷ 0.889 sq ft)
2Fill factor = 1 for every cell, or 8 ÷ spacing in inches
3Base volume = blocks ÷ blocks per cubic yard × fill factor
4Order volume = base volume × (1 + waste percentage)
5Bags = ceiling(order volume in cubic feet ÷ product yield)

Standard two-core CMU benchmark

The 100-block and 100-square-foot columns are derived from the same standard face and blocks-per-cubic-yard values used by the calculator. They show base volume before waste.

Block thickness	Blocks per cu yd	Per 100 blocks	Per 100 sq ft
6 inch	120	0.83 cu yd	0.94 cu yd
8 inch	100	1.00 cu yd	1.13 cu yd
10 inch	80	1.25 cu yd	1.41 cu yd
12 inch	65	1.54 cu yd	1.73 cu yd

Sources

Use these references to review the block-fill benchmarks, product yields, and material scope behind the estimate.

Westbrook Concrete Block: Fine Core Fill Grout Yields table for standard CMU thicknesses and wall-area checks.
QUIKRETE Concrete Mix 1101: Product data lists approximate mixed yields of 0.45 cu ft for a 60-lb bag and 0.60 cu ft for an 80-lb bag.
SPEC MIX Core Fill Masonry Grout: Manufacturer information for core-fill grout used in CMU cells and bond beams under the product's stated ASTM C476 scope.
Cemex US Block Calculator: Supplier cross-check that treats block fill as a separate material estimate.

Order ready-mix or bags

Use order volume when speaking with a ready-mix or grout supplier. For bagged material, the calculator divides that same volume by the yield printed on the package and rounds up to a whole bag.

Purchase option	Use this result	Before ordering
Ready-mix or bulk grout	Order volume in cubic yards or cubic meters	Ask the local supplier about delivery limits and project-specific allowances.
80-lb bags	Default yield: 0.60 cu ft per bag	Replace the default with the mixed yield on the actual product package.
60-lb bags	Default yield: 0.45 cu ft per bag	Replace the default with the mixed yield on the actual product package.

Product yield controls bag count only. It does not change the calculated grout volume. Always check the package before purchase.

This page calculates grout volume and bag quantity for purchasing. It does not provide live prices, local supplier quotes, or masonry grout price per cubic yard.

Estimate grout allowance and whole-wall budget for a standard CMU wall

Three ways to check the estimate

These compact examples use standard 8-inch two-core CMU, every cell filled, and no waste so the inputs can be compared directly.

Starting point	Input	Base-volume check
Wall dimensions	20 ft × 8 ft wall	180 blocks ÷ 100 = 1.80 cu yd
Number of blocks	100 standard blocks	100 ÷ 100 = 1.00 cu yd
Filled cores	200 filled cores	200 cores ÷ 2 ÷ 100 = 1.00 cu yd

Scope before you order

This page estimates material for standard two-core concrete masonry units. Keep the takeoff aligned with the project documents and the block manufacturer's data.

Use the grout pattern and reinforcement details from the structural drawings. The calculator does not decide which cores need grout or design reinforcement.
Use Filled cores when the drawings provide an actual count. Spacing modes are planning approximations for a standard two-core layout.
Use the manufacturer's core-volume table for 3-web, 4-web, architectural, or other nonstandard CMU shapes.
Bond beams, lintels, rebar, footings, slabs, and solid walls are outside this estimate.

Frequently asked questions

How much grout fills 100 8-inch concrete blocks?

About 1 cubic yard fills every core in 100 standard 8-inch two-core blocks before waste. With the default bag yields, that base volume equals about 45 80-lb bags or 60 60-lb bags. Add the waste allowance that fits the project and verify the yield on the product package.

How much concrete fills one 8x8x16 block?

The calculator benchmark is 100 standard 8-inch blocks per cubic yard, so one block represents about 0.27 cubic feet of core-fill volume before waste. Actual block shapes vary by manufacturer.

Should every CMU core be filled?

The project drawings should specify which cores are filled. Some walls use every cell, while others grout selected cells. This calculator estimates volume from the pattern you enter but does not choose the pattern or reinforcement.

Can I use concrete mix instead of masonry grout?

Use the material specified for the project. Masonry core-fill grout products state their ASTM C476 scope, while bagged concrete mixes have their own aggregate and yield specifications. Confirm the product with the plans, supplier, or project professional instead of using an unverified site recipe.

Does this calculator include bond beams, lintels, and rebar?

No. The result covers vertical cores represented by the selected mode and fill pattern. Bond beams, lintels, reinforcement, footings, slabs, solid walls, and other separate takeoff items are not included.

Continue the project estimate

For the same standard CMU wall, use the calculator that matches the next material or budget question.