In order to calculate the required quantity of cement plastering, we have to follow the following 3 simple steps.

**Step 1:-Assumptions**

Area of Plaster = 1 m²

Thickness of plaster = 12 mm =0.012 m

Mix Ratio → 1:4

**Step 2:- Quantity of Plaster**

*∵ Volume of plaster = Area of plaster x Thickness of plaster*

Volume of plaster = 1 x 0.012=0.012 m³

**Add 20% extra Quantity for Filling of joints, Depressions & Wastage**

∴Volume of plaster = 0.012 + [ (20×0.012) /100 ] =0.0144 m³

*Dry volume of plaster = Wet volume x 1.35*

Dry Volume = 0.0144 x 1.35 m = 0.01944 m³

**Step 3:- Quantity of Cement**

*Quantity of Cement = (Dry Volume of plaster x Cement ratio) / (Sum of the ratio)*

Quantity of cement = (0.01944 x 1) /(1+4)= **0.003888 m³**

*∵ Density of Cement = 1440 kg/m³*

Weight of Cement = 1440 x 0.003888 = **5.6 Kg**

*∵ 1 bag of cement contains 50 kg of cement*

Number of bags = 5.6 Kg/50 = **0.112 No’s**