The Block CalculatorHow does this block calculator work?
This is the all-purpose version of our tools: it works for concrete, cinder, cement, AAC or clay blocks. Enter the size of the wall and the face size of one block in any unit and the calculator does the conversions. If you need extra detail, use a specialised tool: the block fill calculator for grout volume, the weight calculator for loads, or the red block calculator for bricks with mortar joints and waste.
Tips for accurate estimates
- Subtract openings: work out the area of doors and windows and take it off the wall length or height, or run the calculator for each wall section.
- Use nominal sizes: enter the block size including the mortar joint.
- Count corners and ends: corner and half blocks are often priced separately, so check with your supplier.
Formula used
Total Blocks = (Wall Length × Wall Height) ÷ (Block Length × Block Height)The result is always rounded up to the next whole block, because you can’t buy part of one. Wall thickness is shown in the diagram but does not change the count for a single-wythe wall.
Example
Scenario: A wall 10 m long and 2 m high, built with blocks measuring 40 cm × 20 cm (0.4 m × 0.2 m).
Wall area: 10 m × 2 m = 20 m²
Block face area: 0.4 m × 0.2 m = 0.08 m²
Final result: 20 ÷ 0.08 = 250 blocks. Add 5–10% for cuts and breakage when you order.
Frequently asked questions
Can I use this calculator for AAC or aerated blocks?
Yes. Enter the AAC block face size (for example 600 × 200 mm) and the wall size. AAC is usually laid with thin-bed adhesive, so the joint adds almost nothing to the size.
Does the calculator account for doors and windows?
No. Subtract openings first, or calculate each solid section of wall separately and add the results.
Last updated: . Results are estimates — see our disclaimer.