Block Calculator
Estimate block quantities for a wall, whether you are using lightweight concrete blocks, aerated blocks or dense masonry units.
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Formula and method
Net wall area is divided by the face area of one block, increased by the waste allowance and rounded up. Wall thickness is used to report the volume of blockwork.
How to measure the inputs
- Measure the wall length and height, and count identical walls.
- Measure a block including or excluding the joint, depending on what the manufacturer states.
- Confirm the wall thickness from the drawing.
Worked example
Wall length 16.4 ft; Wall height 9.84 ft; Wall count 1; Openings area (optional) 4.31 ft²; Block length 15.75 in; Block height 7.87 in; Wall thickness 7.87 in; Waste 10 % → Blocks required: 201
Practical tips
- Blocks are heavy: plan deliveries close to where they will be laid.
- Keep blocks dry and covered; aerated blocks absorb a lot of water.
- Cut blocks with the correct saw to keep the face clean.