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Plaster Sand & Cement Calculator

Calculate the quantities of cement and sand required for plastering works. Input the total plaster area, thickness, mix ratio, and wastage to get instant material counts.

Plastering Specifications

Typical: 12, 15, or 20mm.

Required Materials

Cement Required
--
-- kg
Sand Required
--
-- cft
Wet Mortar Volume
--
m³ (cubic meters)
Dry Mix Volume
--
m³ (including waste)

Sand Truck Loads (approximate):

--

Plaster Material Calculation Formula

We calculate material quantities based on wet-to-dry conversion factors and standard component weights:

Wet Volume (V_wet) = Area (m²) × [Thickness (mm) ÷ 1000]
Dry Volume (V_dry) = V_wet × 1.33 × (1 + Wastage % ÷ 100)
Cement Volume = V_dry × [1 ÷ (1 + Ratio_Sand)]
Cement Weight = Cement Volume × 1440 kg/m³
Sand Volume = V_dry × [Ratio_Sand ÷ (1 + Ratio_Sand)]

1.33 Factor: accounts for the shrinkage of cement-sand mix when dry ingredients are mixed with water (dry ingredients shrink by ~33%).

1440 kg/m³: standard bulk density of cement.

Sand CFT Conversion: 1 cubic meter (m³) = 35.315 cubic feet (cft).

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How to use Plaster Sand & Cement Calculator

  1. Enter the wall surface area to be plastered in square meters or square feet.
  2. Enter the design plaster thickness (standard is 12mm to 20mm).
  3. Select the cement-to-sand mix ratio (e.g., 1:3, 1:4, 1:5, or 1:6) and read the sand and cement results.

What is Plaster Sand & Cement Calculator?

Plastering protects and finishes walls using a mortar mixture of cement, sand, and water. When estimating materials, builders must convert the 'wet' volume of plaster into 'dry' volume because dry cement and sand shrink when mixed with water (a shrinkage coefficient of 1.33 is standard). Extra volume must also be added for joint filling and surface unevenness.

This plastering calculator performs all dry volume translations, applies the mix ratio (e.g. 1:4 or 1:6), and outputs the exact weight/bags of cement and volume of sand required.

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FAQ

What is the standard plaster thickness?
For interior walls, plaster thickness is typically 12mm. For exterior brick/concrete surfaces, it is usually 15mm to 20mm, sometimes applied in two coats.
Why does dry volume exceed wet volume in plaster?
Dry cement particles and sand grains contain air voids between them. When water is added, the particles pack closely together and shrink in volume. A factor of 1.33 is used to adjust for this shrinkage.
What is the best plaster mix ratio?
A 1:4 mix (1 part cement to 4 parts sand) is commonly used for ceiling plaster and external walls. A 1:6 mix is standard for internal wall plastering.

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