Inputs
Enter total plaster area or multiply dimensions for walls.
Net openings can be subtracted under Advanced.
Typical interior 10–15 mm; exterior may require more.
Cement
Sand
Example: 1 and 5 equals 1:5 mortar.
Common sizes are 50 kg and 40 kg.
×
Accounts for voids and bulking in dry mortar.
%
Extra to cover handling and site loss.
Total area of windows, doors, or niches.
kg/m³
Typical loose density ~1440 kg/m³.
Results
Cement required
0.000 m³
Dry mortar basis including factors.
Bags required
0.00 bags
Based on selected bag size.
Sand required
0.000 m³
Dry mortar basis for planning.
Wet plaster volume
0.000 m³
Area × thickness before allowances.
Project Rows
Add current inputs to build a comparative list.
| # | Area (m²) | Thk (mm) | Ratio | Dry factor | Wastage % | Bag (kg) | Cement (m³) | Bags | Sand (m³) | Wet vol (m³) | Notes |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 1 | 85.00 | 12 | 1:4 | 1.33 | 5 | 50 | 1.009 | 29.00 | 4.037 | 1.020 | Typical apartment interior plaster |
| 2 | 24.50 | 15 | 1:5 | 1.33 | 7.5 | 40 | 0.344 | 12.38 | 1.719 | 0.368 | Kitchen splash and service walls |
| 3 | 60.00 | 10 | 1:6 | 1.35 | 5 | 50 | 0.462 | 13.21 | 2.772 | 0.600 | Exterior skim with higher factor |
Formula Used
- Wet plaster volume (m³) = Area × Thickness.
- Convert units: 1 ft² = 0.092903 m², 1 in = 25.4 mm.
- Dry mortar volume (m³) = Wet volume × Dry volume factor (typically 1.30–1.35).
- For mix
C:S = c:s,Cement volume = Dry volume × c/(c+s)Sand volume = Dry volume × s/(c+s) - Allow wastage: Multiply both volumes by (1 + wastage%/100).
- Bags = Cement mass / Bag size.
Cement mass (kg) = Cement volume × Cement bulk density (≈1440 kg/m³). - Equivalently, bags = Cement volume / (bag_size / density).
This tool provides planning‑level estimates. Always check local specifications and on‑site conditions.
How to Use
- Select Direct area or enter Length × Height.
- Set plaster thickness and choose your mortar mix ratio.
- Pick bag size; adjust dry factor and wastage if needed.
- Click Calculate to see cement volume, bags, and sand.
- Use Add to project to store a scenario in the table.
- Export results or the table as CSV or PDF for records.
- Refine inputs until the plan aligns with field requirements.
FAQs
1) What dry volume factor should I use?
For plaster mortar, 1.30–1.35 is typical. Start with 1.33 unless specifications prescribe otherwise.
2) Does bag count change with cement brand?
Bag size determines count most. Density varies slightly, but 1440 kg/m³ is a common planning value.
3) Can I enter area in feet and inches?
Yes. Choose ft² for area and inches for thickness. The tool converts to metric internally.
4) How is wastage applied?
Wastage increases dry volumes by your percentage to cover handling and site losses.
5) Does the calculator include water or admixtures?
No. It estimates cement, sand, and bag count only. Water and admixtures are project‑specific.
6) Can I deduct windows and doors?
Yes. Enter the total openings area under Advanced to subtract from plaster area.
7) Are results suitable for procurement?
Use outputs as a baseline. Round up to full bags and confirm against drawings and method statements.