Plastering Rate per Sq Ft — 12 mm vs 20 mm in India
Estimate cement, sand, and material cost per square foot for internal and external wall plaster at common thicknesses and mix ratios.
Plaster quotes on site sound like ₹X per sq ft — but the number hides thickness and mix ratio. A 12 mm internal coat and a 20 mm external coat are not the same cost. Here is how to break it down and use the Plastering Calculator.
Material volume per sq ft
Plaster wet volume per sq ft of wall:
Volume (cft) ≈ thickness (ft)
| Thickness | Wet volume / sq ft | |-----------|-------------------| | 12 mm (~0.47 in) | ~0.039 cft | | 15 mm | ~0.049 cft | | 20 mm (~0.79 in) | ~0.065 cft |
Thicker plaster uses proportionally more cement and sand — jumping 12 mm → 20 mm is ~67% more material, not a small tweak.
Cement and sand per 100 sq ft
Using dry factor 1.33 and 1:4 mix (internal):
| Thickness | Cement bags (approx) | Sand cft (approx) | |-----------|---------------------|-------------------| | 12 mm | ~1 bag | ~4–5 cft | | 20 mm | ~1.5–2 bags | ~7–8 cft |
1:6 external mix uses less cement for the same volume — see how much cement and sand for plastering.
Material cost per sq ft (planning bands)
At ₹400/bag and ₹55/cft (edit to your local rates):
| Thickness | Mix | Rough material / sq ft | |-----------|-----|------------------------| | 12 mm | 1:4 | ₹4–7 | | 20 mm | 1:6 | ₹5–9 |
Labour for plaster is often quoted ₹15–30 per sq ft depending on city, surface prep, and ceiling vs wall — material and labour are separate lines.
Turnkey plaster rates you may hear
Contractors sometimes quote ₹25–45 per sq ft all-in for standard internal 12 mm plaster — that bundles labour, material, and margin. Use the calculator to see if the material portion (~₹5–7/sq ft) leaves reasonable room for labour in their quote.
FAQ
Double coat — multiply by two?
Two coats of similar thickness → roughly double material. Many external jobs use a rough coat + finish coat at different ratios — run each coat separately in the calculator.
Ceiling plaster — same rate?
Same formula: area × thickness. Ceiling labour is often priced higher per sq ft than walls.
Does plaster cost include primer and paint?
No. This is cement–sand plaster only. Putty, primer, and paint are finishing trades.
Calculate your area — Plastering Calculator. See materials to build a house for where plaster fits in the build sequence.