Cement for plaster = area × thickness × 1.27 ÷ (1 + n) × 1,440 kg/m³ for a 1:n mix. A house with 450 m² of internal walls (12 mm, 1:6), 220 m² external (20 mm, 1:4) and 120 m² of ceilings (6 mm, 1:3) needs about 67 bags of cement and 11 m³ of sand.
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Cement Quantity Calculator (Plastering)
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Total cement for plastering
67.0bags (3,349 kg)
Internal walls (1 : 6)
28.2 bags
External walls (1 : 4)
32.2 bags
Ceilings (1 : 3)
6.6 bags
Total sand
11.03 m³
Bags to buy
67 bags
Cement per m² (average)
4.24 kg/m²
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Generated with myconstructioncalculator.com. Estimates for planning and ordering only; verify against drawings and specifications.
Formula
Wet plaster = area × thicknessDry volume = wet × 1.27Cement (1:n) = dry ÷ (1 + n) → × 1,440 kg/m³ → ÷ 50 kg per bagSand = dry × n ÷ (1 + n)
Worked Example
Zone
Area
Thickness, mix
Cement
Internal walls
450 m²
12 mm, 1 : 6
28.2 bags
External walls
220 m²
20 mm, 1 : 4
32.2 bags
Ceilings
120 m²
6 mm, 1 : 3
6.6 bags
Total
790 m²
67.0 bags (3,349 kg), sand 11.0 m³
Cement per m² of Plaster (kg)
Thickness
1 : 3
1 : 4
1 : 5
1 : 6
6 mm
2.74
2.19
1.83
1.57
12 mm
5.49
4.39
3.66
3.14
15 mm
6.86
5.49
4.57
3.92
20 mm
9.14
7.32
6.10
5.23
Frequently Asked Questions
How much cement is needed for plastering per m²?
About 3.1 kg/m² for 12 mm of 1:6, 4.4 kg/m² for 12 mm of 1:4, and 2.7 kg/m² for 6 mm of 1:3 on ceilings, using the 1.27 dry-volume method.
How many bags of cement for 100 m² of plaster?
About 6.3 bags (50 kg) for 12 mm of 1:6, 8.8 bags for 1:4, and 11 bags for 1:3.
Why are internal, external and ceiling plaster different?
External walls need thicker, richer plaster to resist weather; ceilings take a thin, rich coat so it bonds to concrete; internal walls use a leaner, more economical mix.
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