Block Quantity
Free Block Quantity calculator with clear step-by-step results.
About Block Quantity
A block wall is counted by area, not by length. The face area of one block including its mortar joint tells you how many blocks cover a square metre, and multiplying that by the wall area gives the net count. A 440 × 215 mm block on a 10 mm joint covers 0.0765 m², so roughly 13 blocks fill each square metre. Cutting waste is added on top because every corner, opening and course end produces an off-cut you cannot reuse.
Formulas
Blocks per square metre
Blocks/m² = 1 ÷ ((block length + joint) × (block height + joint))
Order quantity
Blocks to order = ceil(wall area × blocks/m² × (1 + waste))
Worked example
With the default values below, Block Quantity returns Blocks to Order of 250. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Wall areaminimum 0 m²
- 24 m²
- Block face lengthminimum 1 mm
- 440 mm
- Block face heightminimum 1 mm
- 215 mm
- Mortar jointaccepts 0–30 mm
- 10 mm
- Cutting wasteaccepts 0–50 %
- 5 %
Results
- Blocks to Order
- 250 blocks
- Blocks in the Wall
- 238 blocks
- Blocks per m²
- 9.88
- Allowance for Cuts
- 12 blocks
Step by step
- 1Values used
- 2Blocks per square metre
- 3Order quantity
- 4Blocks to Order= 250 blocks
- 5Blocks in the Wall= 238 blocks
- 6Blocks per m²= 9.88
- 7Allowance for Cuts= 12 blocks
Assumptions and limits
- The result is derived only from the 5 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
- A material take-off is not a structural design. Wall thickness, block strength, reinforcement and foundations must be specified by a qualified engineer and comply with your local building code.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
A material take-off is not a structural design. Wall thickness, block strength, reinforcement and foundations must be specified by a qualified engineer and comply with your local building code.
Frequently Asked Questions
Why add the mortar joint to the block size?
The block occupies its own face area plus half a joint on each side, so the repeating module is the block plus one full joint in each direction. Ignoring the joint over-orders by roughly 8-10% on a standard block.
How much cutting waste should I allow?
5% suits a plain rectangular wall. Allow 8-10% where there are many openings, piers or angled cuts, because each cut block usually yields only one usable piece.
Does this include mortar or reinforcement?
No — it returns the block count only. Mortar, wall ties, reinforcement and fill are separate take-offs.