Plaster Calculator

Why Contractors Lose Money Here

Plaster thickness drives everything: every extra 3 mm on a wall is 25% more cement and sand at 12 mm. Uneven brickwork, filled with plaster, quietly doubles consumption on some walls.

Real Site Example

100 m² of internal wall at 12 mm in 1:6: wet 1.2 m³; dry 1.2 × 1.27 = 1.524 m³; +5% = 1.600 m³; cement 1.600 ÷ 7 = 0.229 m³ = 329 kg ≈ 6.6 bags (order 7); sand 1.37 m³ (48 cft).

Professional Best Practices

Fix level dots and screeds first so the thickness is controlled, cure plaster for at least 7 days, and track cement per floor so an over-thick floor shows up early.

Engineering Checklist

• Use 12 mm for internal walls, 6 mm for ceilings, 15–20 mm for external walls (or as specified)
• Check walls for plumb and hollows before plastering
• Use clean, well-graded plaster sand
• Cure for at least 7 days
• Record cement used per floor against the estimate

Government & Standards References

• IS 1661:1972 — Code of practice for cement and cement-lime plaster finishes on walls and ceilings
• IS 1542 — Sand for plaster
• CPWD specifications — plastering

How Experienced Contractors Handle This

Contractors set a cement-per-square-metre target for each plaster type and compare it floor by floor with what the store issued.