Easily calculate wall area for plastering. Enter wall sizes in metric or imperial, get area, plaster quantity & cost. Perfect for DIY & trade projects.
Enter your measurements above to see the results.
Calculate the total wall area (height × width × number of walls), subtract the area of any openings, adjust plaster coverage if thickness is different from standard (12mm/0.5in), then divide net area by the coverage per bag to get bags needed. Total cost is bags needed × price per bag.
Inputs: Metric, 2 walls, height 2.5m, width 4m, openings 2m², thickness 12mm, coverage per bag 10m², price per bag 8.50 GBP. Wall area = 2.5 × 4 × 2 = 20m². Net area = 20 - 2 = 18m². Coverage per bag = 10m² (no adjustment). Bags needed = ceil(18 / 10) = 2. Total cost = 2 × 8.50 = 17.00 GBP.
To calculate the plastering area, multiply the height by the width of each wall, sum the areas for all walls, and subtract the size of any doors or windows. This gives you the net area to be plastered.
Plaster requirements depend on the thickness applied and the coverage per bag. Adjust coverage if your thickness is different from the manufacturer’s standard, then divide the net area by the adjusted coverage to find out how many bags you need.
Standard plaster thickness for walls is usually 12mm (about 0.5 inch). Applying more or less will affect the quantity of plaster required, so always check your project specifications.
The total cost is calculated by multiplying the number of bags needed by the cost per bag. Use the currency selector to get an accurate estimate for your location.
Always measure walls carefully, account for all openings, and double-check coverage rates. For large or complex projects, consider adding a small allowance for wastage.
Multiply the height by the width for each wall, add the areas together, and subtract the total area of any doors or windows to get the net plastering area.
Divide the net plastering area by the coverage provided per bag (adjusted for your chosen plaster thickness). Round up to the nearest whole bag.
Typical plaster thickness for walls is 12mm (0.5 inch). Always check your project requirements and adjust calculations if using a different thickness.
Yes, this calculator supports both metric (metres, mm) and imperial (feet, inches) units. Use the unit system toggle to enter measurements in your preferred system.
Enter the cost per bag of plaster and the calculator will multiply it by the number of bags needed, giving you the total cost in your chosen currency.
