Plaster/plasterboard estimator
Estimate both the plasterboard sheets and the skim plaster needed to board and finish a wall or ceiling.
Result
Plasterboard sheets
Skim plaster
How to use this tool
- Measure the area to be boarded and skimmed.
- Enter how many skim coats you're applying (2 is standard).
- Read the sheets and plaster quantities.
Assumptions
- Assumes 2400 × 1200mm sheets; choose the correct dimensions if using another size.
- The 1.2kg/m²-per-coat default is illustrative only. Actual quantity depends on product instructions, coat thickness, substrate condition and application; check the chosen product's packaging or manufacturer data.
Technical details: what the fields mean
- Wall/ceiling area
areaM2 - Total wall or ceiling area, in square metres.
- Skim coats
skimCoats - Number of coats you plan to apply; check the plaster manufacturer's application instructions.
- Waste allowance
wastePercent - Extra plasterboard for cuts around openings and board edges.
Methodology
Sheet count = (area × (1 + waste%)) ÷ 2.88m², using the assumed 2400 × 1200mm board size. Skim plaster estimate = area × 1.2kg/m² per coat × coats. The board-area division is geometry; the editable waste allowance and plaster rate are planning assumptions, not guaranteed product yields.
Worked example
12m² ceiling, 2 skim coats, 10% board waste
Inputs: Wall/ceiling area: 12 m², Skim coats: 2, Waste allowance: 10%
Result: 5 sheets, 28.8kg skim plaster
Practical guidance
- Buy a couple of spare plasterboard sheets — breakages during handling are common.
- Plaster is usually sold in 25kg bags; round the kg figure up to whole bags.
Common mistakes
- Forgetting that ceilings need the same waste allowance as walls for cut edges.
- Underestimating plaster on a rough or uneven substrate, which needs more material than a flat one.
FAQs
How many plasterboard sheets do I need for a 12m² ceiling?
5 standard 2400 × 1200mm sheets, allowing the default 10% waste.
How much skim plaster do I need per square metre?
This estimate uses an illustrative 1.2kg/m² per coat. Check the chosen plaster's coverage and application instructions; actual use varies with substrate and coat thickness.
Last reviewed: 2026-10-11
Board count assumes 2400 × 1200mm sheets and a user-selected waste allowance. Plaster quantity is approximate; use the chosen product's stated coverage and instructions.
This tool provides an indicative estimate, based on the assumptions stated above.
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