CMU Wall Design Calculator
Calculate concrete masonry unit (CMU) block count, rebar, grout, and mortar for a block wall.
Inputs
Results
Blocks Required
180 blocks
How to Use This Calculator
- Enter the wall height and length in feet.
- Enter the block width in inches (8, 10, or 12 are most common) and the vertical rebar spacing.
- Optionally enter a grouted cells override, or leave it at 0 to auto-calculate from rebar spacing, and enter any opening area to subtract.
- Review the blocks required, vertical rebar bars, grout volume, and mortar bags.
- Consult a structural engineer before building load-bearing CMU walls.
How the result changes with Wall Height
| Wall Height | Blocks Required |
|---|---|
| 4.9 | 120 blocks |
| 15 | 345 blocks |
| 26 | 585 blocks |
| 36 | 810 blocks |
What each input means
- Wall Height
- Height of the CMU wall from footing to top course.
- Wall Length
- Total horizontal length of the block wall.
- Block Width
- Nominal block width: 8, 10, or 12 inches are most common.
- Vertical Rebar Spacing
- Center-to-center spacing of vertical rebar (typically 24-48 in).
- Grouted Cells Override
- Number of cells to grout per course. Enter 0 to auto-calculate based on rebar spacing.
- Openings Area
- Total area of door and window openings to subtract.
How this is calculated
Worked example, using the default values
- Identify Input Parameters4 parametersWall Height = 8, Wall Length = 20, Block Width = 8, Vertical Rebar Spacing = 48 = 6 input(s) provided
- Calculate Blocks RequiredBlocks Required180 = 180
- Calculate Vertical Rebar BarsVertical Rebar Bars6 = 6
- Calculate Grout NeededGrout Needed0.07 = 0.07
Engine last updated . Checked against 1 independently-derived test — how we verify calculators.
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