Plan smooth finishes by checking thickness across surfaces. Built for site measurements, coats, and openings. Save calculations, share totals, and reduce costly rework today.
| Surface (L×H) | Openings | Coats | Wastage | Wet Volume | Estimated Thickness |
|---|---|---|---|---|---|
| 6.0 m × 2.8 m | 1.9 m² | 2 | 8% | 120 L | ~4.0 mm |
| 4.5 m × 3.0 m | 1.2 m² | 1 | 10% | 0.06 m³ | ~5.0 mm |
| 12 ft × 9 ft | 12 ft² | 2 | 7% | 3.5 ft³ | ~0.20 in |
1) Gross area
Agross = L × H
2) Net area
Anet = Agross − Aopenings
3) Coated area (multiple coats)
Acoated = Anet × coats
4) Wastage factor
fw = 1 + (wastage% / 100)
5A) Thickness from material
Convert wet volume to cubic meters, then:
t = (V × fw) / Acoated
Where t is thickness (meters), V is wet volume (m³).
5B) Material from target thickness
V = Acoated × t, then apply wastage: Vw = V × fw
6) Mass conversion (optional)
V = mass / density and mass = V × density
Accurate plaster planning starts with reliable surface area. Measure length and height for each wall face, then subtract doors and windows. When shapes are irregular, use direct area entry from takeoff sheets. Split areas by room, elevation, or substrate so you can track productivity across all elevations. Applying separate areas for different backgrounds avoids mixing rates and improves control over final thickness.
Thickness is driven by system type, flatness tolerances, and exposure. Skim coats typically refine texture, while base coats correct undulations and protect masonry. External renders often require more build for durability and weather resistance. Where straightness is critical, consider guides and set out levels before work begins. Use the calculator to compare coats and check whether the implied thickness aligns with the chosen specification range.
Material yield links wet volume, density, and coated area. If you know mixed volume, the calculator converts it to cubic meters and applies wastage. If you track bags, enter total mass and use a realistic density for your mix. Density varies with sand grading, water content, and additives, so confirm from a test batch. Adjust wastage to reflect spray rebound, hawk losses, and trimming around openings.
Field verification reduces rework. Spot-check thickness using depth gauges, screed guides, or marked pins at multiple locations. Confirm that coats are evenly distributed, especially at corners and junctions. Allow proper keying between coats and respect curing times for cement-rich materials. If calculated thickness is low, increase volume or coats rather than pushing a single heavy pass that can slump or crack.
Consistent records support costing and variation claims. Save results as CSV for quick rollups by zone and date, and keep the PDF with daily reports. Note the assumed density, wastage, and number of coats so later comparisons remain fair. Record ambient conditions and substrate moisture when issues arise. Repeat calculations when conditions, mix design, or crew method change.
Yes. Enter the ceiling area as gross area or use equivalent dimensions. Include openings like skylights where relevant, and increase wastage if overhead work causes more loss.
Use the density of your mixed material if known. If unsure, start with a typical value and refine after a test batch. Density changes with water content, aggregates, and additives.
Each coat covers the same net area. Multiplying by coats converts net area into coated area, ensuring volume and mass estimates reflect multiple passes rather than a single layer.
Use lower values for careful hand application and higher values for spray work, complex geometry, and frequent interruptions. Start at 8–12% and adjust based on site history.
Verify net area, openings, and coats first. Then confirm volume units and density. If inputs are correct, increase material volume or add coats to meet the required build.
Yes. After you calculate, the tool stores the result for that browser session. The download buttons export the saved values, including area, coats, wastage, thickness, and density.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.