Calculator Inputs
Enter project values. Output updates after you press Calculate.
Example Data Table
Use this sample to validate your setup and confirm unit rates.
| Parameter | Example Value | Notes |
|---|---|---|
| Area | 120 m² | Interior wall plaster |
| Thickness | 12 mm | Single coat average |
| Mix ratio | 1 : 4 | Cement : sand |
| Cement rate | ₨ 1350 / bag | Local supply rate |
| Sand rate | ₨ 4500 / m³ | Delivered at site |
| Labor rate | ₨ 250 / m² | Includes finishing |
| Wastage | 5% | Handling + rebound |
| Overhead | 8% | Supervision + admin |
| Profit | 10% | Contract margin |
Formula Used
- Convert area:
Area(m²) = Area(ft²) × 0.092903 - Wet mortar volume:
Vwet = Area(m²) × Thickness(m) - Dry mortar volume:
Vdry = Vwet × DryFactor - Cement volume:
Vc = Vdry × (1 / (1 + SandParts)) - Sand volume:
Vs = Vdry × (SandParts / (1 + SandParts)) - Cement mass:
Mc(kg) = Vc × CementDensity - Bags:
Bags = Mc / BagWeight - Base cost:
Materials + Labor + Scaffolding + Other - Wastage:
WastageCost = BaseCost × Wastage% - Subtotal:
Subtotal = BaseCost + WastageCost - Overhead:
Overhead = Subtotal × Overhead% - Profit:
Profit = (Subtotal + Overhead) × Profit% - Tax:
Tax = (Subtotal + Overhead + Profit) × Tax% - Grand total:
Total = Subtotal + Overhead + Profit + Tax
How to Use This Calculator
- Enter your plaster area and select the correct unit.
- Set thickness and choose a mix ratio (or custom).
- Confirm dry factor and cement density if needed.
- Fill in cement, sand, and labor rates for your market.
- Add scaffolding and transport if your scope includes them.
- Set wastage, overhead, profit, and optional tax percentages.
- Press Calculate to view the full breakdown.
- Use Download CSV or Download PDF for sharing.
Plaster Cost Estimating Guide
Plaster work is often priced quickly, yet small assumptions can move the final bill noticeably. A reliable estimate begins with measuring the true surface area, selecting a realistic thickness, and confirming the mortar mix ratio used on your site. This calculator turns those inputs into material quantities and an itemized cost breakdown, so you can prepare budgets, compare bids, and manage variations with confidence.
Start with area and thickness. Measure net wall and ceiling area after deducting large openings when required by your method of measurement. Thickness should reflect the specified average finish. For many interior jobs, a 10–15 mm coat is common, but repairs and leveling can push thickness higher. Because thickness directly drives mortar volume, even a 2 mm change can affect cement bags and sand volume on larger areas.
Understand wet and dry volume. Plaster quantity is calculated from wet volume (area × thickness) and then converted to dry volume using a dry factor. The dry factor covers bulking, voids, and handling losses during mixing and application. If your team has historical consumption records, replace the default with your project’s proven factor for better accuracy.
Mix ratio controls cement demand. For a 1:4 cement-to-sand mix, cement is one part out of five total parts. The calculator splits dry volume into cement and sand volumes using the chosen ratio, converts cement volume to kilograms using cement density, and then converts kilograms to bags using your bag weight. This ensures your procurement list matches how materials are purchased and stored.
Costs are built from rates and allowances. Material cost includes cement, sand, and optional additives per square meter. Labor, scaffolding, and transport are added to form a base cost, then wastage is applied as a percentage to cover typical losses. Overhead and profit are calculated afterward so you can see how business markups impact the final rate. Optional tax can be included to match invoicing requirements.
Example: For 120 m² at 12 mm thickness with a 1:4 mix, cement at ₨ 1350/bag, sand at ₨ 4500/m³, labor at ₨ 250/m², wastage 5%, overhead 8%, and profit 10%, the calculator will generate cement bags, sand volume, and a complete cost total with unit rates for tendering.
For best results, align inputs with your specifications, verify rates with current supplier quotes, and export the report (CSV/PDF) to attach to your estimate files or client submissions.
FAQs
1) Should I measure plaster area in m² or ft²?
Use whichever unit your drawings and BOQ follow. The calculator converts ft² to m² automatically using 0.092903. Consistency matters more than unit choice.
2) What thickness should I enter for interior plaster?
Enter the specified average thickness. Many interior coats fall around 10–15 mm, but leveling and repairs can increase it. If unsure, use a measured average from site checks.
3) Why is a dry volume factor used?
Wet volume does not equal the loose materials needed. The dry factor accounts for bulking, voids, and practical losses during mixing and placement. Adjust it if you have verified consumption data.
4) How do I choose the mix ratio?
Select the ratio required by your specifications or engineer. A richer mix (like 1:3) uses more cement, while 1:5 uses less cement but may affect performance depending on application.
5) Can I include additives and bonding agents?
Yes. Enter an additive cost per m² to cover bonding agents, waterproofing, fibers, or polymers. This keeps the material cost aligned with the full scope of work.
6) Where should I apply overhead and profit?
This tool applies overhead after wastage, then calculates profit on subtotal plus overhead. That structure matches many estimating practices and keeps margins transparent for review.
7) How accurate is the final cost?
Accuracy depends on measurements, rates, and realistic allowances. Use current supplier quotes, validate thickness, and tune wastage/dry factor from past projects. Treat results as an estimate, not a final bill.