How it works
Calculate your material requirement
Estimate concrete masonry units for a wall, subtract openings, and include an allowance for cuts and breakage.
The formula
Blocks = (wall area − openings) ÷ nominal block face area, increased by the selected waste allowance.
Worked example
A 30 ft × 8 ft wall with a 21 ft² opening has 219 ft² of net area. Nominal 16 in × 8 in blocks require about 247 units before waste.
Before you order
- Nominal block dimensions typically include the mortar joint.
- Calculate walls of different heights separately.
- Bond pattern, corners, bond beams, and specialty units can change the order.