Concrete Block Calculator
Estimate CMU blocks for a wall with mortar joints, openings and wastage.
How to use this tool
- Enter wall length and height.
- Set block length/height and joint thickness.
- Add openings.
- Set wastage and cost per block.
- Calculate blocks, area and mortar volume.
How it works
Net area = wall area − openings. One block plus joint occupies (len+j) x (h+j). Blocks = net area / unit area. Mortar volume is derived from the joint volume plus typical wastage.
Tips
- Order by the pallet where possible — check pallet counts with your supplier.
- Include full and half blocks for corners and openings.
- Add 10% wastage for cuts and breakage.
Limitations
Half-blocks and lintel units are assumed within wastage; complex bond patterns change counts.
Frequently asked questions
How many concrete blocks are there per square foot?
A standard 16x8 in CMU block with a 3/8 in joint covers about 0.89 sq ft, so roughly 1.125 blocks per sq ft. Actual count depends on your block and joint sizes.
What size is a standard block?
Nominal 8x8x16 in (400x200x200 mm nominal). The calculator takes any length and height.
Do openings come out of the count?
Yes — subtract doors, windows and lintel zones for a tighter estimate.