How many concrete blocks do I need?
Enter wall area and block face coverage. A common 8 x 8 x 16 block covers about 0.89 sq ft with a standard joint, so 160 sq ft with 10% waste needs about 198 blocks.
Openings and wall layout
Windows, doors, corners, returns, bond pattern, control joints, cuts, and damaged units can change the final count. Estimate different wall sections separately when dimensions change.
Material count is not wall design
This page estimates quantity only. Structural design, reinforcement, footing, drainage, code requirements, and engineered wall details are separate from the calculator result.
Masonry unit coverage reference
Coverage varies with unit size and joint layout. Use actual units and bond pattern for final takeoff.
| Unit | Planning face coverage | Units for 160 sq ft with 10% waste |
|---|---|---|
| 8 x 8 x 16 CMU / concrete block | 0.89 sq ft | 198 blocks |
| Modular brick face example | 0.22 sq ft | 800 bricks |
| General building material | Use product coverage | Divide area by unit coverage, then add waste |
Mortar and mix planning checks
Mortar and sand-cement coverage changes with joint size, wall thickness, mixing loss, and bag yield.
| Material | Use this input | Separate from |
|---|---|---|
| Mortar / mortar mix | Product coverage per bag | Brick or block count, reinforcement, flashing |
| Sand and cement mix | Bag yield or volume yield | Structural mix design and code requirements |
| Core fill / grout | Cell volume and filled-cell count | Blocks, rebar, bond beams, lifts |
Before you calculate
- Measure wall face area in square feet.
- Use the actual block, brick, or product coverage for the selected material.
- Calculate sections with different unit sizes, bond patterns, or openings separately.
Common mistakes
- Using nominal unit size without considering mortar joints and face coverage.
- Forgetting openings, corners, cuts, caps, mortar, grout, and reinforcement.
- Treating a material count as wall design.
Formula
units = ceil((area * (1 + wastePercent / 100)) / coveragePerUnit)
Assumptions
- Block face coverage depends on the actual unit size, orientation, and mortar joint.
- Openings, corners, bond beams, lintels, caps, mortar, grout, and reinforcement are separate unless included manually.
- Use supplier coverage, layout drawings, and local code requirements before ordering final material.
Example
Estimated concrete hollow block needed (blocks): 248 blocks
How to calculate CMU blocks
- Measure wall area in square feet and separate wall sections when height, thickness, or block type changes.
- Enter block face coverage from the selected CMU, concrete block, or ICF block size.
- Subtract only planned openings when the takeoff method calls for it, then add waste for cuts, corners, and breakage.
- Divide adjusted wall area by block coverage and round up to whole blocks; the default example returns 248 blocks.
- Estimate mortar, grout, rebar, bond beams, lintels, drainage, waterproofing, and inspection requirements separately.
Before you buy materials
- Round up to full pallets, bags, or units as sold by the supplier.
- Confirm mortar, grout, rebar, flashing, drainage, and delivery separately.
FAQ
How much area does an 8 x 8 x 16 block cover?
A common planning value is about 0.89 square feet per block face with a standard mortar joint.
How many concrete blocks for 160 sq ft?
Using 0.89 sq ft per block, 160 sq ft needs about 180 blocks before waste, or about 198 blocks with 10% waste.
Should I subtract windows and doors?
Subtract large openings for a detailed takeoff, but keep waste for cuts, corners, breakage, and layout changes.
Does this include mortar or rebar?
No. Blocks, bricks, mortar, grout, rebar, anchors, flashing, and labor should be estimated separately.
What is the example masonry blocks result?
Using the default inputs, the example result is 248 blocks. Estimate masonry blocks from wall area, block face coverage, openings, and waste, then round up to whole blocks.
Related calculators
This calculator is for planning estimates only. Verify final quantities with product labels, project conditions, and a qualified professional when accuracy matters.