Plaster Calculator
Calculate cement plaster quantities, bags of sand, and costs for South African building projects. Covers 1 to 3 coat systems, premixed plaster, Rhinolite skim coat, and paint coverage.
Quick Calculator Get a fast estimate
m²
%
Area to plaster
50 m²
Plaster volume
0,862 m³
Cement bags (50kg)
7
Building sand
1,29 tonnes
Labour cost
R 6 000
Material cost
R 1 748
Total estimated cost
R 7 748
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How to Use the Plaster Calculator
Enter the wall area, select the number of coats and plaster type, and the calculator gives cement bags, sand tonnage, and estimated costs including labour.
The Extended Calculator computes net area after deducting doors and windows, and includes ceiling Rhinolite skim quantities. The Professional Calculator covers paint coverage, crack repair diagnosis, and plaster system comparison.
Need more detail?
Extended Calculator More options, charts, and scenario comparison
m
m
mm
m²
m²
Wall plastering
46,2 m² net
Gross area
54 m²
Openings deducted
7,8 m²
Cement bags (50kg)
6
Building sand
1,2 t
Labour cost
R 5 544
Plaster Mix Ratios and Thicknesses
Volume = area × thickness (m) × (1 + wastage)
Cement bags = Volume × 7 (for 1:4 mix)
Sand (tonnes) = Volume × 1.5
Standard thicknesses:
1 coat (finish only): 8 mm
2 coats (scratch + finish): 15 mm
3 coats (rough + scratch + finish): 20–25 mm
Plaster Type Comparison
| Type | Mix | Use | Cost/m² |
|---|---|---|---|
| Cement plaster 1:4 | 1 cement : 4 sand | Standard walls | R180–R280 |
| Rich mix 1:3 | 1 cement : 3 sand | Exposed / external | R220–R320 |
| Premixed bagged | Factory blended | Small areas, DIY | R250–R380 |
| Rhinolite skim | Gypsum compound | Ceiling / finish coat | R150–R250 |
| Textured acrylic | Polymer binder | Feature walls | R300–R480 |
Need full precision?
Professional Calculator Complete parameters, sensitivity analysis, and detailed breakdown
m²
m²/L
R/L
Paint quantities
20 litres
Total area to paint
200 m² (2 coats)
5L tins needed
4
Paint cost
R 1 300
Typical coverage rates
PVA 8–12 m²/L; Enamel 12–16 m²/L
Frequently Asked Questions
2-coat system (15mm): ~0.7 bags cement and 150kg sand per m². Add 15% wastage. Premixed plaster: 1.5–2 bags (25kg) per m². Rhinolite skim (5mm): ~1 bag (5kg/m²) per m².
1:4 (cement:sand) for standard internal walls. 1:3 for external and wet areas. 1:5 for partition walls and low-stress areas. Use clean building sand (not sea sand) and add plasticiser for workability. Mix dry, then add water.
2 coats for most internal walls: scratch coat (10mm, rough finish) + finish coat (5mm). Rough brick or blockwork may need a spatterdash first. Ceilings get 1 coat Rhinolite skim (3–5mm) over hardboard or skim plaster board.
Cement plaster: minimum 28 days (full cure). Rhinolite: 3–7 days. Test with a moisture meter — must be <15% before applying PVA primer. Painting wet plaster causes bubbling and delamination. New plaster needs alkali-resistant primer.
Labour R90–R150/m². Materials (cement + sand): R80–R150/m². Total 2-coat system: R180–R300/m². Rhinolite skim: R150–R250/m². Textured render: R300–R480/m². Prices vary by city — Cape Town and Johannesburg are typically 10–20% higher.