Free Construction Calculators & Tools/Plastering & Rendering Calculator

Plastering & Rendering Calculator

Calculate cement and sand quantities for plastering walls and ceilings. Supports various mix ratios (1:3 to 1:6), multiple plaster thicknesses, and provides accurate material estimates for internal and external rendering.

Wall Specifications

Total surface area to be plastered

Mix Design

Internal walls

Mix Ratio Guide
1:3External render and wet areas on strong backgrounds
1:4Internal walls
1:5Internal partitions and ceilings
1:6Low-strength backgrounds

Enter wall specifications and click Calculate to see materials

Notes:

  • Dry volume is 33% more than wet volume (mortar shrinkage)
  • 1:4 ratio is standard for internal plastering
  • 1:3 to 1:4 for external render and wet areas; 1:5 to 1:6 only for weaker backgrounds
  • Add 5-10% extra for wastage in actual ordering
  • Water quantity varies with sand moisture content
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ESTIMATION NOTICE

This calculator provides APPROXIMATE QUANTITIES for budgeting and planning purposes.

Please note:

• Results include standard wastage factors but actual waste may vary based on site conditions, workmanship, and material quality.

About This Calculator

The Plastering & Rendering Calculator helps contractors and quantity surveyors estimate cement and sand quantities for wall and ceiling finishes across UAE and Gulf projects. Calculate accurate material requirements based on surface area, plaster thickness, and mortar mix ratios. Essential for BOQ preparation and material procurement for internal plastering, external rendering, and decorative finishes in residential and commercial buildings.

When to Use This Calculator

  • Preparing BOQ for plastering and rendering works
  • Estimating cement and sand for internal wall finishes
  • Calculating materials for external rendering in Gulf climate
  • Planning multi-coat plaster systems (scratch, brown, finish)
  • Verifying subcontractor material requirements

How to Use This Calculator

1

Enter Surface Area

Input total wall or ceiling area in square meters, or calculate from room dimensions.

2

Select Plaster Thickness

Choose thickness: 12mm for internal walls, 15-20mm for external rendering, 6mm for ceiling.

3

Choose Mortar Mix Ratio

Select mix ratio: 1:3 for external, 1:4 for internal walls, 1:5 for ceilings.

4

Deduct Openings

Enter door and window areas to deduct from total plastering area.

5

Calculate Results

Get cement bags, sand volume, and water requirements with wastage allowance.

Typical Scenarios in UAE & Gulf Projects

Villa Internal Plastering in Dubai

A villa has 400 m² of internal wall to plaster at 12 mm in one coat with a 1:4 cement:sand mix. The calculator gives 4.8 m³ of wet mortar, 6.38 m³ of dry materials (+33% for voids and bulking), 1,839 kg of cement (37 bags of 50 kg) and 5.11 m³ of sand, about 10.8 m² per bag.

Tower External Rendering in Saudi Arabia

A residential tower needs 8,000 m² of external render at 20 mm with a 1:3 mix. The calculator gives 160 m³ of wet mortar, 212.8 m³ of dry materials, 76,608 kg of cement (1,533 bags of 50 kg) and 159.6 m³ of sand, about 5.2 m² per bag. Waterproofing or polymer admixtures are specified separately and are not included.

Frequently Asked Questions

Recommended thicknesses: Internal walls 12-15mm (single coat) or 20mm (two-coat), External rendering 18-25mm (two-coat minimum), Ceilings 6-10mm, Concrete surfaces 10-12mm with bonding agent. In Gulf climate, external rendering needs minimum 20mm for thermal and humidity protection.

Mix ratios by application: 1:3 (cement:sand) for external rendering and wet areas, 1:4 for internal load-bearing walls, 1:5 for internal partitions and ceilings, 1:6 only for low-strength backgrounds. Use a mix no stronger than the background. Gulf conditions often require waterproofing admixture for external and bathroom plaster.

Using the calculator's method (dry volume = wet volume × 1.33, cement at 1,440 kg/m³): at 12 mm with a 1:4 mix, about 4.6 kg of cement and 0.013 m³ of sand per m², so a 50 kg bag covers about 10.8 m². At 20 mm with a 1:3 mix, about 9.6 kg of cement and 0.020 m³ of sand per m², about 5.2 m² per bag. Add site wastage as needed.

Take Your Calculations Further

This calculator reflects the logic built into Arkan's construction management platform.

Last Updated: January 2026

Standards Reference: Plaster specifications per BS EN 13914 and ASTM C926

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