Concrete blocks, also called CMUs (Concrete Masonry Units), are economical and strong building materials for walls, foundations, and structures. This calculator determines block quantities based on wall dimensions.
Standard blocks measure 8x8x16 inches (width x height x length), though actual dimensions are 7.625x7.625x15.625 to allow for mortar joints. You'll need 1.125 blocks per square foot. Narrower 6-inch and 4-inch blocks are available for non-load-bearing partition walls.
Blocks come in various types: standard hollow core for general construction, solid blocks for heavy loads, and insulated blocks with foam inserts for energy efficiency. Half blocks and corner blocks simplify construction at wall ends and openings.
Proper foundation and rebar reinforcement are essential for block walls. Fill cores with concrete and rebar per local codes. Apply waterproofing to below-grade walls. Surface finishes include stucco, paint, or leaving exposed for industrial aesthetics.
Quick Tips
- Always order 10-15% extra materials for waste
- Check local building codes before starting
- Measure twice, cut once — verify all inputs
Frequently Asked Questions
1.125 standard blocks (8x8x16) per square foot with standard mortar joints.
The width: 6-inch for partitions, 8-inch for standard walls, 12-inch for retaining walls.
Load-bearing walls and walls with rebar must have cores filled per code requirements.
Type N for above grade, Type S for below grade or load-bearing applications.
Small projects are DIY-friendly with practice, but foundations and tall walls should be professional.