Quick Guide: How Many Cinder Blocks Per Square Foot?
The most common question in masonry is how many blocks are required for a specific wall size. If you are using standard 8x8x16 cinder blocks, the math is relatively simple because each block covers 0.89 square feet of wall surface area (including the 3/8" mortar joint).
The Rule of 1.125
1.125 Blocks per SQ FT
To find your count quickly, multiply your total square footage by 1.125.
Standard Coverage
75% of a Block
One standard 8x8x16 block covers roughly 0.89 square feet of the wall face.
How Many Cinder Blocks for Common Wall Sizes?
Here is a quick reference chart for standard 8x8x16 cinder block counts (including a 10% waste factor):
| Wall Size (Feet) | Total Area | Blocks Needed |
|---|---|---|
| 10' Long x 4' High | 40 sq ft | ~50 Blocks |
| 20' Long x 4' High | 80 sq ft | ~100 Blocks |
| 50' Long x 6' High | 300 sq ft | ~375 Blocks |
| 100' Long x 8' High | 800 sq ft | ~1000 Blocks |
Steps to Calculate Manually
- Calculate Square Footage: Multiply length by height (e.g., 20ft x 5ft = 100 sq ft).
- Adjust for Block Size: Divide your square footage by the block's face area (0.89 for standard blocks).
- Subtract Openings: If you have doors or windows, subtract their square footage from the total before dividing.
- Add Waste: Multiply the total by 1.10 (10% waste) to account for cuts and breaks.