Plaster Calculator
Work out how many bags of plaster you need for a wall or ceiling, plus the cost — from the area and coat thickness. Free, instant, no sign-up.
Wall / area
Price
Your plaster estimate
Area30,0 m²
Plaster bags (40 kg)22 bags
Estimated plaster costR 2 090
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Create a free account →How the plaster calculation works
volume (m³) = area × (thickness_mm ÷ 1000) mass (kg) = volume × 1700 × (1 + waste%) bags = ⌈mass ÷ bag weight (40 kg)⌉ plaster cost = bags × price per bag
FAQ
- How do I calculate how much plaster I need?
- Multiply the area by the coat thickness to get the volume, convert to mass using the plaster density (~1700 kg/m³), add ~10% waste, then divide by the bag weight. This calculator does it for you.
- How thick should a plaster coat be?
- A typical sand-cement plaster coat is 12–20 mm; a skim / topcoat is 2–3 mm. Thicker coats on uneven walls use proportionally more material.
- How many square metres does a bag of plaster cover?
- It depends on thickness. At 15 mm, a 40 kg bag covers roughly 1.5 m². Thinner coats cover more area per bag.
- Does this include labour?
- This estimates plaster material only. Create a free BuilderBuddi account to build the full plastering estimate with labour and your margin.
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