How Many Concrete Blocks Do You Need?
Enter the wall dimensions, choose the CMU size, and add waste to get a whole-block order count.
Last updated: September 7, 2026
Thickness does not change the 8x16 face count. Use the size specified for your project.
Concrete Block Order Summary
189
blocks to buy
- Wall area
- 160 sq ft
- Base count
- 180 blocks
- 5% waste
- 9 blocks
- CMU size
- 8x8x16 nominal
Count uses the nominal 8x16 block face with a 3/8-inch mortar joint. Subtract large openings before ordering, then confirm availability and return policy with your supplier.
Use this block count to calculate mortar bagsConcrete Block Order Examples
| Project | Dimensions | Area | Base Count | Order with 5% |
|---|---|---|---|---|
| Garden wall | 10 x 4 ft | 40 sq ft | 45 blocks | 48 blocks |
| Straight wall | 20 x 8 ft | 160 sq ft | 180 blocks | 189 blocks |
| Non-module wall | 17.5 x 9.25 ft | 161.88 sq ft | 183 blocks | 193 blocks |
Frequently Asked Questions
Multiply the wall length by its height to get the wall area, then divide by the face area of one block. A nominal 8x8x16 CMU covers about 0.89 square feet with a standard 3/8-inch mortar joint, or about 1.125 blocks per square foot before waste. Add your waste allowance and round up to whole blocks to buy.
For a planning estimate, subtract large openings from the gross wall area before entering dimensions. Small openings may not reduce the purchase count much because cut blocks and breakage still consume material.
Use 5% for a simple rectangular wall with few cuts. Use 10% when the layout has several corners, openings, or cut ends. Confirm the final quantity and return policy with your supplier.
Not when the blocks share the same nominal 8x16 face. A 4-inch, 6-inch, 8-inch, 10-inch, or 12-inch CMU covers the same wall face area; thickness changes the wall assembly, not the face count. Use the size shown on your plans or specified for the project.
Mortar yield depends on block thickness, joint width, bag size, and product yield. Use the block count from this page in the Mortar Calculator rather than treating a generic cement-and-sand ratio as a premixed mortar-bag estimate.