Gypsum Plaster Calculator: How Many Bags for Your Walls
Base layer on walls and ceilings.
- 1Dimensions
- 2Result
Material
Plaster
Typical room
What we calculate
Openings (doors and windows)
The plaster calculator above tells you exactly how many bags to buy before you start. It uses the standard formula: 0.9 kg per m² for every 1 mm of thickness, plus a 10% wastage allowance built in. For a typical 10 mm levelling coat, that works out to around 9.9 kg per square metre of wall or ceiling.
Below you will find a quick guide on how gypsum plaster consumption works, how to read the results and what to watch for when applying it.
How to calculate plaster quantity - formula and example
The formula is straightforward:
Quantity (kg) = area (m²) x thickness (mm) x 0.9 kg/m²/mm x 1.1 (10% wastage)
Example: 20 m² of walls at 10 mm thickness:
- 20 x 10 x 0.9 = 180 kg
- 180 x 1.1 = 198 kg with wastage
- In 25 kg bags: 198 / 25 = 8 bags
- In 30 kg bags: 198 / 30 = 7 bags
If your walls are uneven, increase the thickness input to 15-20 mm. Subtract door and window areas before calculating.
A note on brands: Each brand states its own consumption in the technical datasheet. Figures may differ from 0.9 kg/m²/mm - check the datasheet of your chosen product before ordering.
Gypsum vs cement plaster - which to choose
Gypsum-based plaster is the standard choice for interior walls and ceilings. It gives a smooth, paintable surface and is lighter than cement render. Cement plaster is used in wet areas and on exterior surfaces.
Brands at Colorista.md: Knauf, Baumit, Ceresit, Atlas, Weber, Supraten - stocked locally in Chisinau, prices in MDL.
- Prime absorbent surfaces (AAC block, porous brick) with a penetrating primer
- Set metal guide profiles (screeds) to control layer thickness
- Mix plaster into cold water, not the other way around
- Embed fibreglass mesh at joints between different materials and at corners
Why buy from Colorista.md
Colorista.md is operated by StialitGE SRL, with a physical warehouse in Chisinau and delivery across Moldova. All brands are officially supplied: Knauf, Baumit, Ceresit, Atlas, Weber, Supraten. Orders can be picked up or delivered to your address.
Frequently asked questions
How many kg of gypsum plaster per m2 at 10mm thickness?
At 10 mm thickness, the consumption is approximately 9 kg/m² (0.9 kg per m² per mm). With a standard 10% wastage allowance, that comes to about 9.9 kg/m². The calculator above includes this allowance automatically.
How many bags of plaster do I need for 20 square metres of walls?
Using the formula: 20 m² x 10 mm x 0.9 kg = 180 kg, plus 10% = 198 kg. That is 8 bags of 25 kg or 7 bags of 30 kg. If your walls are uneven, enter the actual thickness in the calculator.
Do I need a primer before applying gypsum plaster?
On highly absorbent surfaces like AAC block or porous brick, a penetrating primer is strongly recommended. On dense concrete, some products can be applied directly - check the technical datasheet for the specific product you choose.