Free Plaster Calculator: Cement and Sand

How the quantities are worked out

Wet plaster = area × thickness. Dry mortar = wet plaster × 1.33, plus your wastage.

Cement bags = dry mortar ÷ (1 + sand parts) ÷ 0.0347. Sand = dry mortar × sand parts ÷ (1 + sand parts).

Example: 100 m² at 12 mm is 1.2 m³ wet, or 1.38 m³ with 15% extra. Dry, that is 1.84 m³. At 1 : 4, cement is 0.37 m³ or about 10.6 bags, and sand is 1.47 m³.

Rough brickwork takes more than smooth blockwork, so raise the extra if your walls are out of line. Thickness and mix are common site practice. Your engineer’s specification comes first.

Questions people ask