Plaster quantity calculator
Estimate the cement bags and sand for cement plaster on a wall or ceiling, from its size, thickness and mix, with doors and windows taken off.
How much cement and sand for 100 sq ft of plaster?
At 12 mm thick with a 20% allowance, 100 sq ft of plaster needs about 0.98 bags of cement and 4.8 cft of sand in a 1:4 mix, and about 0.70 bags and 5.1 cft in a 1:6 mix. Enter your own sizes above.
| Mix | 12 mm, no allowance | 12 mm, 20% allowance | 15 mm, no allowance | 15 mm, 20% allowance |
|---|---|---|---|---|
| 1:3 | 1.02 | 1.22 | 1.27 | 1.53 |
| 1:4 | 0.82 | 0.98 | 1.02 | 1.22 |
| 1:5 | 0.68 | 0.82 | 0.85 | 1.02 |
| 1:6 | 0.58 | 0.70 | 0.73 | 0.87 |
How is the quantity worked out?
The calculator takes the area of plaster, takes off the larger doors and windows, and multiplies by the thickness to get the volume of wet mortar. It multiplies that by 1.27 to get the dry volume of cement and sand needed, and splits it by the mix. For a 1:4 mix, one part in five is cement and four parts in five are sand. It changes cement volume to bags using 1,440 kg per cubic metre and a 50 kg bag, adds your allowance, and rounds the cement up to whole bags.
What does it assume?
- Cement-sand plaster only. Lime mixes, gypsum plaster, bonding agents, mesh and special finishes are not included.
- The dry-volume factor of 1.27 and the default allowance of 20% are estimating conventions used on this site, not figures from an Indian Standard. Plaster loses more mortar than brickwork, so 5% will usually run short.
- Sand is shown as loose dry volume. No allowance is added for damp sand, so order extra if your sand is wet.
- Doors and windows over 0.5 m² are taken off in full, and nothing is added back for their sides. The Indian Standard measures large openings a little differently, so your contractor's measurement may differ slightly.
- The mix, thickness and number of coats for your wall are decided by your engineer. IS 1661 lists single-coat plaster at 10 to 15 mm and does not assign a mix to a type of wall.
Sources
- IS 1661:1972, Code of Practice for Application of Cement and Cement-Lime Plaster Finishes (thicknesses; 1,440 kg per cubic metre for cement).
- IS 1200 (Part 12):1976, Method of Measurement of Building and Civil Engineering Works: Plastering and Pointing (area measurement and openings).
- IS 1542:1992, Sand for Plaster.
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General information only. It is not a structural design or professional advice. Ask a licensed structural engineer or architect to check your plans and site.