Construction & Material Estimator
Plaster & Paint Coverage Estimator
Calculate cement bags, sand in CFT and brass, wall putty, primer, and paint litres for internal walls, external masonry plastering, or ceiling coats.
10% to 15% standard for joint depressions & rebound
Material Cost Estimator (Optional)
Materials & Coverage Summary
Net: 1,000 sq.ft (92.9 m²)Plastering Mortar Breakdown (12mm, 1:5)
Formula and assumptions
- Mortar dry volume is 1.33× the wet volume to account for void ratio and dry shrinkage.
- Wastage allowance accounts for joint filling, uneven brick/block depressions, and site rebound losses.
- Cement bulk density is 1,440 kg/m³ with 50 kg per statutory cement bag.
- River / M-sand dry bulk density is 1,600 kg/m³ with 1 Brass = 100 Cubic Feet (CFT).
- Wall putty coverage assumes ~12 sq.ft/kg for 2 standard coats (40 kg bags).
- Wall primer coverage assumes ~130 sq.ft/litre for 1 coat.
- Interior/Exterior paint coverage assumes ~60 sq.ft/litre for 2 finish coats.
- Half-up rounding for monetary values and material decimals; ceil for bags to buy.
Formula version CPWD DSR 2023 / IS 1661:1972 (Cement Plaster) & Standard Painting Norms, last reviewed 2024-10-01.
Frequently asked questions
What is the recommended mortar ratio for internal and external plastering?
According to IS 1661:1972 and CPWD specifications, internal brick walls typically use 1:5 or 1:6 cement-sand mortar at 12 mm thickness. External walls exposed to weather require a richer 1:4 or 1:3 mix at 15 mm (single coat) or 20 mm (double coat with waterproofing). RCC ceilings use a rich 1:3 or 1:4 mix at 6 mm thickness.
Why is the dry volume of mortar 1.33 times the wet volume?
When dry cement and sand particles are mixed with water, the fine cement particles fill the microscopic voids between sand grains, causing volume shrinkage. Civil engineering practice applies a dry volume factor of 1.30 to 1.33 (30% to 33% increase) to ensure sufficient dry materials are purchased to yield the target wet plastered volume.
What is 1 Brass of sand in Indian construction?
In India (especially in Maharashtra, Gujarat, Karnataka, Madhya Pradesh, and Goa), bulk construction materials like sand, aggregate, and rubble are sold in 'Brass'. 1 Brass equals exactly 100 Cubic Feet (CFT), which corresponds to approximately 2.83168 cubic metres (m³) or ~4.5 metric tonnes of dry sand.
How much wall putty is needed per square foot?
Standard white cement-based acrylic wall putty covers approximately 10 to 14 sq.ft per kg for two coats on smooth plastered walls (~12 sq.ft/kg average). Rough or uneven external plaster may require more putty. Wall putty is commonly packaged in 20 kg and 40 kg bags.
What is the coverage of wall primer and emulsion paint?
Water-based interior or exterior wall primer provides a coverage of 120 to 140 sq.ft per litre for a single coat. Interior acrylic emulsion or exterior weatherproof paint gives 110 to 130 sq.ft per litre for 1 coat, which translates to 55 to 65 sq.ft per litre for the recommended 2-coat finish.
How much water is required for plaster mortar mixing?
Generally, approximately 28 to 32 litres of clean potable water is required per 50 kg bag of cement for 1:4 to 1:6 plastering mortar to achieve optimal workability without inducing excessive shrinkage cracks.