CMU Block Calculator

By CalculatorBolt Team | Jan 15, 2025

Calculate the number of CMU blocks needed for a wall. Enter wall dimensions, block size, mortar joint thickness, and waste factor. Get total blocks, mortar volume, and estimated weight.

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Calculate Blocks Needed

Actual: 7.625×7.625×15.625 in
Typical: 3/8 in (0.375)
Typical: 5-10%

How it Works

Blocks per row = Wall Length ÷ (Block Length + Mortar Joint). Rows = Wall Height ÷ (Block Height + Mortar Joint). Total Blocks = Blocks per row × Rows. We apply a waste factor and calculate mortar volume and estimated weight.

Example

Wall 20×8 ft, Standard 8×8×16 block, 3/8 in joint, 5% waste:

  • Blocks per row = 240 ÷ (15.625+0.375) ≈ 15
  • Rows = 96 ÷ (7.625+0.375) ≈ 12
  • Total = 180; Adjusted = 189
  • Mortar ≈ 0.55 cu yd; Weight ≈ 2.4 tons

Tips & Notes

  • Mortar joint thickness is typically 3/8 in (10 mm).
  • Add a waste factor (5–10%) for breakage and cuts.
  • Block density varies; use manufacturer's data for accurate weight.

FAQs

Nominal 8×8×16 in; actual dimensions are slightly smaller (7.625×7.625×15.625 in).

The calculator estimates mortar volume based on joint thickness and block dimensions.

⚠️ Disclaimer

Informational estimate only. Block dimensions and mortar properties vary by manufacturer. Consult suppliers for accurate estimates.

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