Skim Plaster Calculator — Consumption and Cost 2026

Skim plaster consumption is roughly 0.8–1.2 kg/m² per coat about 1 mm thick. With two coats you use about 2 kg per m². For 50 m² of wall with two coats at 1 kg/m²/coat you need about 100 kg, i.e. four 25 kg bags.

Two coats are standard: a first levelling coat and a second finishing coat. On very uneven walls or for higher requirements (walls under raking light, high-gloss paint) three coats are used. Each coat is applied after the previous one has dried.

The number of bags is calculated by dividing total consumption (kg) by the bag weight (usually 25 kg) and rounding up. It is worth buying a 5–10% reserve for losses during mixing, sanding and touch-ups. The calculator rounds up to whole bags automatically.

A 25 kg bag of gypsum skim plaster in Poland (2026) costs roughly PLN 35–60 depending on brand and type (gypsum, polymer, ready-mixed paste). Polymer plasters and ready pastes are more expensive but more convenient. The calculator defaults to PLN 45 per bag.

Labour for skimming walls in Poland (2026) is roughly PLN 12–25/m² for two coats with sanding. The price depends on wall condition, region and scope (skimming only or with priming). The calculator uses an average rate of PLN 15/m².

Gypsum skim is cheaper, easy to work with and breathable, but sensitive to moisture. Polymer skim is more elastic, crack- and moisture-resistant and gives a smoother surface, but costs more. For bathrooms and damp rooms polymer is the better choice.

The wall should be cleaned of dust and loose plaster and primed to reduce and even out the substrate absorbency. Priming improves adhesion and prevents the plaster from drying out too fast. Once the primer has dried, the first coat can be applied.

Gypsum skim usually dries in 24 hours per coat at room temperature and normal humidity before it can be sanded and the next coat applied. In cold or damp rooms the time extends. Full drying before painting takes 1–3 days.

Yes. Smooth, even substrates (plasterboard) use less plaster (about 0.8 kg/m²/coat), while uneven cement-lime plasters need a thicker levelling coat and more material (up to 1.5 kg/m²/coat). Enter the realistic consumption for your substrate for a more accurate result.

Results are indicative and based on average consumption values and market prices in Poland 2026. Actual consumption depends on coat thickness, substrate condition, application technique and material losses. A final estimate is best confirmed with a contractor.