Quality Inspector
Plastering Work
Plaster Calculator (2026) – Cement, Sand & Gypsum Quantity Tool
Expert Guide
Calculate cement, sand & gypsum for walls and ceilings with 1:3, 1:4 and 1:6 ratios.
⚡ Quick Answer
For standard 1:4 internal plaster (12.5mm), you need ~1 bag of cement for every 80 sq.ft. Ceiling plaster (6mm) uses ~1 bag per 160 sq.ft. For localized plastering labor rates, visit pro.nirmansutra.com.
🛠️ How It Works
- •Select your surface: Ceilings require thinner mortar (6mm), while external walls often need 20mm.
- •The tool applies a 25% extra volume factor for filling mortar joints and surface unevenness in masonry.
- •A 33% dry volume expansion is added to account for shrinkage and voids in the raw cement-sand mix.
📐 Calculation Formula
Theoretic Vol = Area × Thickness
Wet Vol (Compensated) = Theoretic Vol × 1.25 (Joints/Unevenness)
Dry Vol = Wet Vol × 1.33 (Shrinkage)
Cement = (Ratio_Part1 / Ratio_Sum) × Dry Vol / 0.0347
📋 Real-Life Example
Example: Plastering a 10m x 5m wall @ 12.5mm (1:4).
1. Theoretic Volume = 50 * 0.0125 = 0.625 m³.
2. Compensated Wet Vol (x1.25) = 0.781 m³.
3. Dry Volume (x1.33) = 1.039 m³.
4. Cement = (1/5) * 1.039 / 0.0347 ≈ 6 bags.
5. Sand = (4/5) * 1.039 * 35.31 ≈ 29 CFT.
⚠️ Common Mistakes to Avoid
- ✕Ignoring dry volume expansion factor (1.33) — cement mortar shrinks significantly when mixed with water.
- ✕Using a lean 1:6 ratio for ceilings — always use a rich 1:3 or 1:4 mix for better overhead adhesion.
- ✕Not deducting major openings (doors/windows) from the area — this leads to 10-15% over-ordering.
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प्लास्टरको सिमेन्ट र बालुवाको हिसाब
Ghar plaster garna kati karch huncha
❓ Frequently Asked Questions
A 1:4 (Cement:Sand) ratio is the engineering standard for internal wall plastering in Nepal and India.
For a standard 12.5mm (0.5 inch) internal plaster with a 1:4 ratio, you need approximately 1.2 to 1.4 bags of cement.
Cement mortar shrinks when water is added. We multiply the wet volume by 1.33 to find the "Dry Volume" needed to order the correct raw materials.
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Worth NRs. 5,000
NRs. 999 🎯
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