Plaster Calculator
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Enter the area to plaster, the thickness and the mortar ratio, and get the cement and sand. Works for internal walls, external walls and ceilings.
Plaster Calculator
Cement and sand to plaster any wall or ceiling area
Plaster on wall
Cement–sand mortar 1:6 · dry ×1.33
Wall length × height, or use the area calculator for odd shapes.
Cement for plaster
6.6 bags
100 m² at 12 mm · 1:6
Cement (50 kg)
6.6 bags
Sand (cft)
48.3
Sand (m³)
1.37
Wet mortar
1.20 m³
Full material take-off
Cement bags
6.6
Sand (m³)
1.37
Sand (cft)
48.3
Sand (t)
2.19
Wet mortar
1.20 m³
Dry mortar
1.60 m³
Cost estimate — edit to your local rates
| Material | Quantity | Rate (₹) | Amount |
|---|---|---|---|
| Cement | 6.6 bags | /bag | ₹2,497 |
| Sand | 48.3 cft | /cft | ₹2,899 |
| Total (materials) | ₹5,395 | ||
Indicative — type today's local rates. Labour is separate: see the material price lists and labour rates.
Plaster in one coat where you can — two thin coats use more material than one. For external faces use 1:4–1:5 and 15 mm; ceilings need ~20 mm. Turn area into cost with the cement price list and labour rates.
How it works
- Wet mortar = area × thickness.
- Dry material = wet × 1.33 (sand bulks up when wet; the dry ingredients are more than the wet volume).
- Cement and sand are split from the dry volume by the mix ratio — for 1:6, one part in seven is cement, six parts sand. One 50 kg cement bag is 0.0347 m³.
Worked example
Plaster 100 m² of internal wall at 12 mm in 1:6 mortar:
- Wet mortar = 100 × 0.012 = 1.2 m³
- Dry material = 1.2 × 1.33 = 1.6 m³
- Cement ≈ 6.6 bags, sand ≈ 1.37 m³ (48.3 cft)
Typical thickness & ratio
| Surface | Thickness | Ratio |
|---|---|---|
| Internal wall | 12 mm | 1:6 |
| External wall (rough coat) | 15–20 mm | 1:4–1:5 |
| Ceiling / soffit | 6–20 mm | 1:4 |
| Neeru / finish coat | 3–6 mm | 1:3 or lime |
Frequently asked questions
How much cement is needed for plastering 100 sq m? About 6–7 bags for a 12 mm internal plaster in 1:6, along with roughly 1.37 m³ of sand. Thicker external plaster or a richer mix needs more.
How do I calculate plastering quantity? Multiply the area by the thickness for wet mortar, multiply by 1.33 for dry material, then split by the mix ratio into cement and sand. The calculator does all three steps.
Why multiply by 1.33? Dry sand and cement occupy more volume than the finished wet mortar because of voids and bulking, so the dry ingredients are about 1.33 times the wet plaster volume.
How many coats of plaster? One coat is normal for internal walls (12 mm). External walls often get a rough base coat plus a finish coat; add the thicknesses.
Related
CivilSite Editorial Team✓ Engineer reviewed
Written and reviewed by practising civil engineers with 10+ years of Indian residential construction experience.