Plaster and Mortar Calculator
The materials needed for plastering by surface area.
Tip: Average plaster thickness: 1.5–2 cm. Uneven surfaces need more material.
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About this digital tool
The plaster and mortar calculator gives you the amount of cement, sand and water for plastering walls, starting from the area and the thickness of the layer. Choose whether the job is interior plaster, exterior plaster or bricklaying mortar, enter the area in m² and the thickness in mm.
The volume of mortar comes out as the area multiplied by the thickness (in metres), then 15% waste is added for every drop from the wall and for cleaning the bucket. From this volume, the kilograms of cement, 25 kg bags, cubic metres of sand and litres of water are calculated. The tool serves plasterers, owners renovating a home and anyone who wants to buy the right material without overdoing it.
How to use
- Choose the type of work: interior plaster, exterior plaster or bricklaying mortar.
- Enter the area you will plaster, in m².
- Set the layer thickness in millimetres.
- Read the mortar volume, the cement bags, the sand and the water needed.
Frequently asked questions
How much material is needed for 1 m² of plaster?
For a thickness of 1.5 cm: ~20–25 kg of ready-mixed mortar per m², or ~6 kg of cement + ~18 kg of sand if mixed on site.
How thick should plaster be?
Thickness depends on the wall surface and the type of plaster; uneven surfaces need a thicker layer. In the tool you can change the thickness in mm and instantly see how much material is added.
How is the wall area for plastering calculated?
Add up the area of each wall (length × height) and subtract doors and windows. Enter the total in m² in the area field.
How much water is needed for plaster mortar?
The tool estimates water as 0.45 litres per kilogram of cement. It is an indicative value; the exact amount varies with the moisture of the sand, so add the water gradually while mixing.