Concrete Block Calculator

How the calculation works

Quantity = wall area/((block length + joint) × (block height + joint)) × (1 + waste/100). Millimeter measurements are converted to meters before calculating area.

Inputs

• Net wall area, m²
• Block length, mm
• Block height, mm
• Joint thickness, mm
• Waste, %

Calculation details

Subtract windows and doors from wall area. If the manufacturer lists nominal dimensions that already include the joint, set the joint thickness to zero.

Block width determines a single-leaf wall's thickness, but not units per square meter. Lintels, reinforcement, and special blocks need separate quantities.