Does this subtract windows and doors?

No. Subtract openings manually from wall area before running the calculation for more accuracy.

Are mortar joints included?

Use nominal block sizes (e.g., 16×8 includes a 3/8 in joint). If your blocks differ, adjust the dimensions.

How much waste should I use?

8–12% is common. Increase waste for projects with lots of cuts or specialty shapes.

Do I still need rebar and grout?

Yes. Structural requirements depend on code and design. This calculator only estimates block counts.

Can I convert this to pallets?

Divide the block total by the number of blocks per pallet from your supplier, then round up.

construction calculator

Block Wall Calculator

Estimate cinder block counts for a wall with waste allowance.

Results

Wall area (sq ft): 240.00
Blocks needed: 297.00

How to use this calculator

Enter wall length and height in feet.
Enter CMU block size in inches and a waste allowance.
See wall area and estimated block count with waste included.

Inputs explained

Wall length/height: Overall wall dimensions in feet.
Block length/height: Nominal CMU size including mortar joint (e.g., 16×8 in).
Waste allowance: Extra percentage for cuts, breakage, and layout adjustments.

How it works

Wall area = length × height.

Block area = block length × height. Blocks = area ÷ block area × (1 + waste).

Formula

Blocks = (Wall area ÷ Block area) × (1 + waste)

When to use it

Ordering pallets of CMUs for garages, sheds, or foundation walls.
Budgeting material before accounting for openings and lintels.
Comparing block sizes to see how counts change for the same wall footprint.

Tips & cautions

Typical CMU nominal size is 16×8 inches with a 3/8 inch mortar joint—match your block dimensions to the supplier spec.
Add extra waste for many openings or complex layouts.
Remember to order specialty blocks (corners, bond beams) separately; this estimate is for standard units.
Does not subtract doors/windows or add lintels and bond beams.
Assumes consistent block size and standard mortar joints.
Reinforcing steel, grout fills, and engineering are not included.

Worked examples

30 ft × 8 ft wall, 16×8 in blocks, 10% waste

Blocks ≈ 270

20 ft × 6 ft wall, 16×8 in blocks, 8% waste

Blocks ≈ 145

Deep dive

This block wall calculator estimates CMU counts from wall length, height, block size, and waste. Enter your dimensions to get a quick block tally before calling the yard.

Use it for garages, sheds, and foundation walls, then add openings, lintels, and reinforcement separately. Increase waste if you expect heavy cutting or many openings.

FAQs

Does this subtract windows and doors?: No. Subtract openings manually from wall area before running the calculation for more accuracy.
Are mortar joints included?: Use nominal block sizes (e.g., 16×8 includes a 3/8 in joint). If your blocks differ, adjust the dimensions.
How much waste should I use?: 8–12% is common. Increase waste for projects with lots of cuts or specialty shapes.
Do I still need rebar and grout?: Yes. Structural requirements depend on code and design. This calculator only estimates block counts.
Can I convert this to pallets?: Divide the block total by the number of blocks per pallet from your supplier, then round up.

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Add extra for specialty blocks, openings, and lintels.