What mix ratio should I use for internal plaster?
1:4 or 1:5 cement-to-sand is common for internal walls. External plaster may use 1:4 with additives.
Plaster Material Calculator
Estimate cement and sand quantities for wall plaster by area, thickness, mix ratio, and wastage.
Plaster Material Calculator Formula
- Plaster Area
Wall Length × Wall Height × Surfaces - Wet Volume
Area × Plaster Thickness - Dry Volume
Wet Volume × 1.33 (bulking allowance) - Material Split
Dry volume split by cement : sand ratio
Assumptions
- Dry volume uses a 33% bulking factor for sand in mortar.
- Sand density is approximated at 1600 kg/m³ for weight estimates.
- Surface finish, bonding agents, and mesh reinforcement are excluded.
Frequently Asked Questions
When should I select two surfaces?
Choose two surfaces when plastering both sides of a wall, such as a partition.
Does this include skim coat?
Enter the total finished plaster thickness. Add extra wastage if multiple coats are applied separately.