Block wall estimating
Estimate how many concrete blocks or cinder blocks you need for a wall. Enter the wall dimensions, choose a standard block size or custom size, then calculate block count, mortar bags and material cost. The calculator automatically defaults to imperial units for countries such as the United States and metric units for most other countries.
Concrete block result
Enter wall and block dimensions below, then calculate your estimate.
concrete blocks
Mortar is estimated at 3 standard bags per 100 blocks. Consider ordering a small extra allowance for cuts, breakage and site variation.
How to use
Measure the planned wall height and width, choose the block face size, then calculate the number of blocks. The result rounds up because you cannot buy partial concrete blocks.
Reference
The calculator converts all lengths into feet internally, then compares the wall face area with the face area of one concrete block.
wall area = wall height x wall width
block area = block height x block width
blocks = wall area / block area, rounded up
total cost = number of blocks needed x price per block
mortar bags = number of blocks needed / 33.3, rounded up
Country units
Visitors in the United States, Liberia and Myanmar see feet and inches by default. Visitors in most other countries see meters and millimeters by default. You can still switch units manually at any time.
Wall dimensions default to feet, and common block face sizes default to inches such as 16 in x 8 in.
Wall dimensions default to meters, and common block face sizes default to millimeters such as 400 mm x 200 mm.
Use custom size when your supplier lists a local block size, nominal block size or masonry unit that differs from the presets.
FAQ
Multiply wall height by wall width, divide by the face area of one block, then round up. Add extra blocks for waste, cuts and breakage.
Use the block size specified by your plan, engineer or local supplier. A common U.S. block face is 16 in x 8 in, while many metric blocks are around 400 mm x 200 mm.
The preset sizes are practical face-size estimates for planning. If your supplier gives exact modular dimensions including mortar joints, enter those dimensions as a custom block size.
A 5% to 10% waste allowance is common for many block walls. Complicated layouts, corners and lots of cuts may need more.
A rough rule is three standard bags for 100 blocks. Manufacturer coverage, joint thickness, block type and installation method can change the actual amount.