Concrete block calculator — CMU count for a wall

Enter wall length and height in feet. Block size is the nominal face size, which includes a 3/8 in mortar joint (a 16 × 8 in face covers 0.889 ft²).

Tool und Bezeichnungen sind auf Deutsch. Die Referenzhinweise darunter bleiben auf Englisch.

concrete block calculator

Wall length (ft)Wall height (ft)Openings area (ft²)Nominal block length (in)Nominal block height (in)Waste allowance (%)

TaskBider drafters, detailers and BIM coordinators work remotely and every listing shows the pay. Typical published range for this work: $18–$45/hr.

blocks = ceil((L × H − openings) ÷ (block L × block H ÷ 144) × (1 + waste/100))

Corners, bond beams, lintels and cut blocks are counted separately on real takeoffs.

Input	Result
20 × 8 ft wall, 8×16 block, 5%	160 ÷ 0.889 = 180 × 1.05 = 189 blocks
40 × 4 ft, no waste	180 blocks

1.125 for standard 8 × 16 in nominal blocks.

112.5, so buy 119 with 5% waste (rounded up).