The Cement Block Calculator tells you how many concrete or cinder blocks you need for a wall, accounting for mortar joints and waste. Simply fill in the fields above and click Calculate to get an instant result.
This calculator is part of Calculate Wiki’s Construction Calculators collection.
What You’ll Need
- Wall Length and Wall Height
- Block Length and Block Height — standard is 16 in × 8 in
- Mortar Joint Width
- Waste Allowance
Formula Used
Blocks per sq ft = 144 ÷ ((Block length + Joint) × (Block height + Joint))
Total blocks = Wall area × Blocks per sq ft × (1 + Waste%)
Example Calculation
Using example inputs — Length = 20 ft; Height = 8 ft; Block = 16 in × 8 in; Joint = 0.375 in; Waste = 10% — the Cement Block Calculator returns:
| Value | Result |
|---|---|
| Wall area | 160 sq ft |
| Blocks per sq ft | 1.107 |
| Blocks needed | 195 |
195 blocks needed.
Helpful Information
Results from the Cement Block Calculator are estimates based on standard formulas used in the construction calculators field. Block sizes vary by region and manufacturer — check your specific block’s dimensions.