Cinder Block Calculator Guide
Concrete masonry units (CMU), commonly called cinder blocks, are a fundamental building material for foundations, retaining walls, and structural walls. Standard cinder blocks measure 8×8×16 inches (nominal) and cover 0.89 square feet of wall area per block when accounting for mortar joints.
Standard Block: 8" × 8" × 16" (nominal)
Blocks per sq ft: 1.125 blocks
Mortar per 100 blocks: ~8.5 bags (80lb)
Average cost: $1.50-3.50 per block
How to Measure
Measure the total wall length and height. Multiply to get square footage. Then multiply by 1.125 to get the number of blocks needed. Add 5-10% for waste and breakage.
Mortar Requirements
Standard mortar joints are 3/8 inch thick. You will need approximately 8.5 bags of 80-lb pre-mixed mortar per 100 blocks. Type S mortar is recommended for below-grade and structural applications.
Cost Estimates
Standard gray blocks cost $1.50-2.50 each. Split-face decorative blocks cost $2.50-5.00. Professional labor adds $5-15 per square foot installed.
How to Use
Enter the wall length and height. The calculator estimates blocks needed, mortar bags, and total cost in real time.
Construction Tips
Always install rebar in cells for structural walls. Fill cores with concrete for added strength. Waterproof below-grade walls. Use proper footings sized for your soil conditions.