Plaster Calculator
Estimate plaster/rendering material volume and bags for walls and ceilings.
How to use this tool
- Enter wall/ceiling area (length x height).
- Set thickness and mix ratio (or custom parts).
- Choose bag size and sand unit cost.
- Add wastage and calculate cement/sand quantities.
How it works
Plaster volume = area x thickness. With ratio C:S, cement volume = total/(1+ratio) and sand volume = total x ratio/(1+ratio). Convert volumes to bags using bulk densities.
Tips
- Allow extra for uneven walls — add 5–10% wastage.
- First coat (scratch) and finish coat may need different mixes.
- Big jobs are cheaper in ready-mixed plaster from a supplier.
Limitations
Bulk density assumptions (e.g., 1440 kg/m³ cement, 1600 kg/m³ sand) approximate real world bags.
Frequently asked questions
What mix ratio is used for wall plaster?
Common ratios are 1:4 and 1:6 (cement : sand). The calculator defaults to 1:6 and lets you choose or enter ratios.
How thick is wall plastering?
Typically 12–15 mm (0.5–0.6 in) for a final coat on walls, or 6 mm for ceilings. Enter your required thickness.
How much wall area does a bag of plaster cover?
It depends on thickness. At 12 mm with a 1:6 mix, a 50 kg bag covers roughly 1.2–1.5 m². The calculator computes exact values.