Calculator
A quick estimate before you order. Your builder or engineer gives the final figure from the drawings.
Blocks for a wall
Length × height minus openings, times the blocks per square metre.
You need about 0 blocks Net area: 0 m²
Based on 12.5 blocks per square metre (40 × 20 cm block face).
Facade stone & interlock
Area plus a waste allowance for cuts and corners — usually 5–10% for stone.
You need about 0 m²
Area multiplied by the waste allowance for cuts and breakage.