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Plaster Calculator
Estimate plaster materials for walls
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Result
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What this calculator does
Estimates kilograms of plaster for a wall from its area and the thickness of the coat.
How to use it
- Enter wall width and height.
- Enter the coat thickness in millimeters.
- Set waste and read the weight in kilograms.
Formula
Area = Width × Height kg = Area × Thickness × 1.2 × (1 + Waste Margin (%) / 100)
Formulas are shown in metric units, exactly as the calculator computes them. Imperial entries are converted to metric first. Waste is applied as a multiplier (1 + waste/100).
Areas are in m² and volumes in m³.
Variables
| Variable | Unit | Default |
|---|---|---|
| Width | m | 4 |
| Height | m | 2.5 |
| Thickness | mm | 12 |
| Waste Margin (%) | % | 10 |
Worked example
Using the default values of this calculator (Width = 4 m, Height = 2.5 m, Thickness = 12 mm, Waste Margin (%) = 10 %), the calculator returns:
Area = 4 × 2.5 kg = Area × 12 × 1.2 × (1 + 10 / 100)
- Plaster Needed: 158.4 kg
Assumptions and limitations
- Uses a fixed 1.2 kg per m² per mm; actual products differ, so check the datasheet.
- Uneven walls need more than the nominal thickness, and openings are not subtracted.
Waste, rounding and buying
Plaster is sold in sacks; divide the result by the sack weight and round up. Do not mix more than you can apply before it sets.
Frequently asked questions
- How do I use my product coverage?
- Replace the 1.2 kg/m²/mm figure with your datasheet value: multiply it by area and thickness yourself.
- Why is waste important for plaster?
- Uneven substrates and material left in buckets or on tools are common.