How Many Concrete Blocks for a 20x4 ft Retaining Wall?
A 20×4 ft concrete block retaining wall with 5% waste requires approximately 108 standard 8×16 in blocks.
How to use this tool
- Enter the wall length and height in feet.
- Set a waste allowance of 5–10%.
- The result shows wall area and number of 8×8×16 CMU blocks needed.
Estimate the number of standard concrete masonry units (CMUs) needed to build a 20-foot long, 4-foot high retaining wall.
Frequently asked questions
- How many concrete blocks per square foot?
- A standard 8×8×16 CMU block laid with a 3/8" mortar joint covers approximately 0.889 sq ft, so you need about 1.125 blocks per square foot.
- What is a CMU block?
- CMU stands for Concrete Masonry Unit. Standard blocks are 8 inches wide, 8 inches tall, and 16 inches long (nominal dimensions).