Inputs
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CSV & PDF export
All results are estimates. Verify against plans, manufacturer data, and local codes.
Total wall run, excluding returns.
Overall height above footing or slab.
Block module (actual block size without joint)
Default ~ 15.625 in (390 mm) for 16 in module.
Default ~ 7.625 in (190 mm) for 8 in module.
Typical 3/8 in or 10 mm.
Cuts, breakage, and extras.
Estimated halves as a fraction of full blocks.
Add courses of solid caps on top.
Openings (subtract area)
| Width ft | Height ft | Count |
|---|
Rebar & grout (optional)
Distance along wall. Leave blank for none.
Course spacing. Leave blank for none.
Approximate interior cell area grouted where bars occur.
Adjust per product; a practical estimator.
Nominal thickness for context and caps.
Results
Click Calculate to update. All values rounded sensibly.
Net wall area
0 ft² | 0 m²
Blocks (full)
0
Half blocks est.: 0
Cap blocks
0
Mortar bags
0
Vertical rebar
0 bars
Total length: 0 ft / 0 m
Horizontal rebar
0 courses
Total length: 0 ft / 0 m
Grout volume (bar cells)
0 ft³ | 0 yd³ | 0 m³
Example CMU Modules & Block Density
Assuming 3/8 in joints. Effective module = actual size + joint thickness.
| Common CMU | Actual L × H (in) | Module L × H (in) | Blocks / ft² | Blocks / m² |
|---|
Formulas Used
- Gross area: length × height.
- Openings area: sum of (width × height × count) for each opening.
- Net wall area: gross area − openings area.
- Module dimensions: actual block length/height + joint thickness.
- Blocks per ft²: 144 ÷ (module length × module height) in square inches.
- Full blocks: net area (ft²) × blocks/ft², then × (1 + waste%).
- Half blocks: full blocks × half-block allowance%.
- Cap blocks: ⌈wall length ÷ module length⌉ × cap courses.
- Mortar bags: full blocks ÷ blocks-per-bag (adjust to product datasheet).
- Vertical bars count: ⌊wall length ÷ spacing⌋ + 1 (include ends).
- Horizontal courses: ⌊wall height ÷ spacing⌋ + 1.
- Grout volume (bar cells): bars × cell area × wall height, converted to ft³/yd³/m³.
These are practical estimators and do not replace structural design or code requirements.
How to Use This Calculator
- Select your preferred units.
- Enter wall length and height.
- Confirm actual block size and joint thickness; adjust waste and halves.
- Add openings as needed.
- Optionally set rebar spacing and cell area for grout estimation.
- Click Calculate to view results, then export CSV or PDF.
FAQs
Counts are planning estimates using modular dimensions and your waste factor. Actual counts vary with layout, coursing, and site conditions.
Enter the actual block size without joints. The tool adds joint thickness to create the effective modular dimensions.
We use a practical rule: blocks ÷ blocks-per-bag. Adjust the blocks-per-bag value to match your product coverage.
This version estimates grout where vertical bars occur using a user-defined cell area. For full grouting, set cell area to represent the filled cross-section and adjust spacing accordingly.
No. Use this for takeoff planning. Always follow sealed structural drawings and applicable building codes.