Cinder Block Wall Calculator

About this calculator

Block count comes from dividing the wall's face area by a standard block's face area (typically 8"×16", or 0.89 sq ft including a 3/8" mortar joint), then adding a waste allowance of around 5-10%. Mortar bag count is estimated from the number of joints, and vertical rebar is typically specified every 2 to 4 feet along the wall's length, run the full wall height.

Masons, contractors, and DIY builders use this before ordering materials for a concrete block (CMU) wall — a garden wall, foundation, or fence — to avoid both under-ordering (a mid-project supply run) and over-ordering (wasted budget), and to get a rough rebar count for structural reinforcement per local building code.