Concrete Block Calculator
Estimate concrete masonry units and optional mortar bags from wall dimensions, openings and nominal block face size.
How it works
Wall area divided by nominal block face area
For a nominal 8 × 16 inch block face, one block represents about 0.889 square feet of wall before extra material is added.
Blocks = net wall area ÷ nominal block face area × allowance
Bond patterns, half blocks, corners, lintels, reinforcing, grout and structural details are not included.
Why use nominal dimensions?
Nominal masonry dimensions typically represent the block plus its mortar-joint module. Using only the smaller actual molded dimensions can overstate block count.
Is the mortar estimate exact?
No. Mortar yield varies with joint width, block type, waste and bag size. Enter a blocks-per-bag value from your product or supplier.