Plaster / Render Area Calculator
Enter wall length and height, deduct openings, and set coats and thickness to estimate net plaster area and mortar volume for rendering and levelling.
Input Data
Results
At a glance:Net plaster area = (wall length × height − openings) × coats. Mortar volume = net area × thickness(mm)/1000 × (1 + wastage%). Thickness must convert to metres (mm ÷ 1000). Multiple coats accumulate area and thickness by coat count; this calculator simplifies with "coats × single thickness".
Formula
Net area = (length×height − openings) × coats
Mortar volume = net area × thickness(mm)/1000 × (1 + wastage%)
$$A = (L H - O)\,n$$$$V = A \frac{t}{1000}(1+w)$$How to Use
- Enter wall length and height.
- Enter door/window undeducted area.
- Set the number of coats and plaster thickness.
- Set the wastage.
- The tool outputs net area and mortar volume.
Case Studies
Living room external wall
4m×3m, 2 m² openings, single coat, 15 mm, 10% wastage.
Net area 10 m²; mortar 0.165 m³.
Double-coat plaster
5m×2.8m, 1 m² openings, 2 coats, 12 mm, 10%.
Net area 25.2 m²; mortar 0.332 m³.
FAQ
Why deduct openings?
Doors and windows are usually not plastered, so deducting them gives the actual finishing area and avoids over-counting material.
How do thickness and coats combine?
This calculator estimates total mortar by coats × single thickness; if base and finish differ, enter an average.
Related Tools
References
Content review: Calculatorism Construction Team. Results are for reference only; please refer to the relevant authorities for the official figures.