Concrete Block Wall Calculator
Estimate CMU blocks, mortar and reinforcement courses for a wall after openings.
Enter your project details
Each dimension can use its own unit—for example feet for length and inches for thickness. Package counts are rounded up.
Formula and calculation steps
Quantity = adjusted area ÷ product coverage; packages are rounded up.- Start with 120 ft² after openings.
- Add 10% allowance.
- Apply selected product coverage and round up.
Worked example
Use the actual wall area less doors and windows, then select the nominal block face size.
How to use this calculator
- Enter wall size and opening area.
- Select nominal block face size.
- Review block count, mortar and course guidance.
Example: Use the actual wall area less doors and windows, then select the nominal block face size.
Questions about this calculator
What block size should I choose?
Use the nominal face size you will buy (for example 8×16); coverage changes with face dimensions.
Is rebar quantity exact?
Course guidance is a planning aid—follow the structural drawings for reinforcement.
Can I use mixed units?
Yes. Choose feet, inches, metres or centimetres and the calculator converts each input before calculating.
Is this a final material order?
No. Confirm drawings, product coverage, local code and site conditions before buying or building.
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<iframe src="https://www.buildcalclab.com/embed/block-calculator/?theme=light" width="100%" height="640" title="BuildWise calculator" style="border:0;max-width:720px"></iframe>Assumptions and references
Results are estimates based on the dimensions and values you enter. Verify final quantities, manufacturer coverage and site-specific requirements before ordering.
Last reviewed: July 2026 · Read our calculation methodology