Calculator

Plaster, Skim Coat and Screed Calculator (Bags of Dry Mix)

Estimate how many bags of gypsum plaster, cement render, skim coat powder, self-leveling compound or floor screed you need from area and thickness.

By the DIY Guide Editorial Team · Updated · 2 min read

How it's calculated

Dry-mix consumption is usually given by manufacturers as kilograms per square meter per millimeter of thickness. We multiply area × average thickness × consumption rate, add 10% for waste and uneven surfaces, and divide by the bag size. Rates differ between brands, so check your bag and adjust.

Measuring average thickness

Hold a long straightedge or level against the wall or floor in several places and measure the deepest and shallowest gaps. Use the average — and if the difference is large, plan beacons or screed rails so the layer ends up flat.

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