Masonry unit guide
Use net wall area and unit modules for a starting purchase count.
Back to calculator ↑Measure and prepare
Measure wall length, height and openings. Use the block’s laid-face dimensions and the selected system’s joint thickness.
Measure each wall face and record doors, windows and service openings. Identify the face of the unit laid in the wall; do not confuse unit depth with face height. The calculator uses one joint thickness for both bed and head joints. If the chosen system uses different joints, request a product-specific block layout.
How the estimate works
One module occupies (unit length + joint) × (unit height + joint). Divide net wall area by module area, add breakage allowance and round up.
The example wall is 5 × 2.4 = 12 m² minus 2 m² openings, leaving 10 m². The unit module with joints is (0.6 + 0.01) × (0.2 + 0.01) = 0.1281 m². Then 10 ÷ 0.1281 = 78.06 units before allowance; adding 10% gives 85.87, rounded to 86 full units.
Check the order
Confirm unit type, wall thickness and compatible mortar or adhesive. AAC thin-bed systems may use smaller joints.
Check the unit’s label dimensions, wall depth, weight and compatible bonding material. Thin-bed AAC systems need their actual joint size rather than the illustrative 10 mm. A laid-out wall may require half units or specials; list those explicitly. Delivery and carrying units to the work area are separate from the counted pieces.
Limits of the estimate
Have the builder check bonds, cuts, ties and lintels against the actual wall layout.
Area divided by a module does not show actual courses, cuts around openings, ties to columns or lintel requirements. Some offcuts can be reused; others may break beyond the starting allowance. For load-bearing or specified walls, have the wall details reviewed by a qualified builder or engineer before ordering. Check where the wall meets frames or existing walls; junction details may need cut units or additional ties that are outside the unit count.
Common questions
Deduct every opening?
You may deduct area, but small openings still create cuts and waste.
Does AAC adhesive use 10 mm joints?
Do not assume so; enter the chosen manufacturer system’s joint thickness.
Is mortar included?
No. Use the mortar calculator separately.
Sources and calculation guidance
Check these against your chosen product’s label and instructions.