Plaster Bag Calculator
Estimate whole bags from surface area, specified thickness and the product’s mixed yield.
How to use this calculator
- Measure the relevant dimensions and select each input’s unit. Changing units converts your entered value.
- Use the coverage, dimensions or yield for the actual product you plan to buy. The starting numbers are worked examples.
- Calculate, review the assumptions below and check the final order against the project and supplier information.
Formula
Wet volume in litres = area in m² × thickness in m × 1,000. Required volume includes allowance. Bags = round up(required litres ÷ labelled mixed yield per bag).
Worked example
20 m² at 10 mm is 200 L of wet volume. With 10% extra, 220 L at an illustrative 12.5 L/bag rounds to 18 bags.
Common mistakes and limitations
Volume/yield estimate only. Yield is an illustrative input, not a universal product value. Use the manufacturer’s mixed yield, permitted layer thickness and application system; this does not convert bag mass to volume or specify plaster.
Questions about plaster bag
Can I use bag weight as yield?
No. Mass and mixed volume are different. Use the product’s stated mixed yield, or its coverage at the relevant thickness.
Does this recommend a layer thickness?
No. Enter a thickness permitted by the product and appropriate to the project. The default is an arithmetic example only.