CMU Concrete Block Wall Calculator
Calculate the number of concrete masonry blocks, mortar bags, and rebar needed for a block wall.
Enter length and height for a complete material list.
Materials Needed
CMU Block Wall estimates the materials needed for a standard concrete masonry unit wall.
Blocks = (Wall Area / Block Face Area) × 1.05 waste factor
A standard CMU block is 8" × 8" × 16" (nominal, including mortar joint). The actual block is 7⅝" × 7⅝" × 15⅝".
Blocks per square foot: ~1.125 blocks (with ⅜" mortar joints)
Mortar requirements:
- ~8.5 bags (80 lb) of mortar mix per 100 blocks
- Type S mortar for structural/below-grade walls
- Type N mortar for above-grade, non-load-bearing walls
Rebar requirements:
- Vertical: every 4 feet (48") horizontally
- Horizontal: every 4 courses (32" vertically)
- Fill cores with grout at rebar locations
Wall types:
- Non-structural: every 8 ft vertical rebar
- Structural: every 4 ft vertical rebar + horizontal every 4 courses
- Retaining wall: every 2–4 ft vertical + continuous horizontal