Brickwork Calculator
Brick count and brickwork volume for a wall, with opening deduction, mortar joint and wastage %.
Plaster Calculator
Runs on your device Processed locally in your browser. Nothing is uploaded.
Plaster area and quantity for a wall, ceiling or surface, with opening deduction and wastage %.
Length of one surface, in the unit chosen above, up to 3 decimal places.
Height for a wall, width for a ceiling, or the second side for a general surface, in the same unit.
Plaster coat thickness, in the same unit — for example 0.012 m (12 mm) for a typical coat.
A whole number from 1 to 1,000,000.
Total door/window/opening area to deduct from one surface, in the unit's own squared area (for example m² if the unit is m). Defaults to 0.
An adjustable allowance for site cutting and waste, from 0 to 50%. Defaults to 0%.
Result
Enter the values above to see the result.
How to use
This plaster calculator works out plaster area and volume for a wall, ceiling, or general rectangular surface — a practical plaster quantity calculator for site engineers, contractors, masons, and quantity surveyors planning internal or external plaster work.
- Choose the surface type (wall, ceiling, or general rectangular surface) and the unit your dimensions are measured in.
- Enter the surface's length and second dimension (height for a wall, width for a ceiling).
- Enter the plaster thickness — for example 0.012 m (12 mm) for a typical coat.
- Enter the number of surfaces (defaults to 1) and, if there are doors or windows, the total opening area to deduct (defaults to 0).
- Enter a wastage percentage for site cutting and waste (defaults to 0%, up to 50%).
- Read the total plaster volume including wastage, the net plaster area, and the working. Copy or print the result.
Method
- Gross plaster area = length × second dimension (per surface), × the number of surfaces for the total.
- Opening deduction = the opening area you enter (per surface), × the number of surfaces.
- Net plaster area = gross area − opening deduction.
- Plaster volume before wastage = net area × plaster thickness.
- Wastage volume = plaster volume × wastage %.
- Total plaster volume including wastage = plaster volume + wastage volume.
Unit conversions are exact: 1 mm = 0.001 m, 1 cm = 0.01 m, 1 inch = 0.0254 m and 1 foot = 0.3048 m.
Gross plaster area vs. net plaster area. Gross plaster area is the full surface as if it had no openings. Net plaster area subtracts the opening deduction you enter for doors and windows — the figure the plaster volume is actually based on, since plaster is not needed where an opening is. This wall plaster calculator and ceiling plaster calculator both use the same opening-deduction approach.
What plaster thickness should I enter? A typical internal cement plaster coat is around 12–15 mm, and an external coat is often thicker, but actual thickness varies by surface condition and local practice. Enter your own project's specified thickness rather than relying on a single assumed figure.
This calculator gives plaster area and volume only. It does not calculate the cement/sand material breakup, a plaster mix ratio, labour cost, scaffolding, a curing schedule, a bill of quantities (BOQ), or a final billing quantity.
Worked example
A 5 × 3 m wall, 12 mm plaster coat, 1 surface, no opening, no wastage:
| Input | |
|---|---|
| Surface type | Wall |
| Unit | m |
| Length | 5 |
| Second dimension (height/width) | 3 |
| Plaster thickness | 0.012 |
| Number of surfaces | 1 |
| Opening deduction area | 0 |
| Wastage % | 0% |
| Result | |
| Total plaster volume incl. wastage (m³) | 0.180 |
| Net plaster area (m²) | 15.000 |
| Gross plaster area (m²) | 15.000 |
| Opening deduction area (m²) | 0.000 |
| Plaster volume before wastage (m³) | 0.180 |
| Wastage volume (m³) | 0.000 |
| Net plaster area (ft²) | 161.459 |
| Total plaster volume incl. wastage (ft³) | 6.357 |
| Plaster thickness | 0.012 |
| Wastage % | 0% |
FAQ
How do I calculate plaster quantity?
Enter the surface's length, second dimension, and plaster thickness. This plaster quantity calculator multiplies the net area (after any opening deduction) by the thickness to give plaster volume, then adds your wastage allowance.
How do I calculate wall plaster area?
Choose "Wall" as the surface type and enter the wall's length and height. The gross area is length × height; the net area subtracts any door/window opening you enter.
How do I calculate ceiling plaster?
Choose "Ceiling" as the surface type and enter the ceiling's length and width. A ceiling plaster calculator uses the same length × second-dimension formula as a wall — only the label changes.
Should I deduct doors and windows?
Yes, for an accurate estimate. Enter the total door/window area in the opening deduction field; it is subtracted from the gross area before the plaster volume is calculated.
What plaster thickness should I enter?
Use your project's specified thickness for internal or external plaster — commonly 12–15 mm for internal cement plaster, though this varies by site condition and local practice. Always confirm the thickness your project actually specifies.
Does this calculate cement and sand?
No. This calculator estimates plaster area and volume only. A cement/sand material breakup for plaster mortar is a separate calculation this tool does not perform.
Can I use this for final billing?
No. This is an estimation aid for planning and quantity checks, not a final billing quantity or a certified bill of quantities. Actual plaster quantity can vary due to wall unevenness, surface preparation, thickness variation, site cutting, and measurement rules — verify plaster thickness, surface dimensions, openings, and wastage before purchase, billing, or construction, and confirm the final figures with a licensed engineer, architect, contractor, mason, or professional quantity surveyor.
References
- Rectangular area and volume: length × width × thickness (SI, general geometry).
- International yard and pound agreement (1959): 1 inch = 25.4 mm and 1 foot = 304.8 mm exactly.
- Cubic foot: 1 ft³ = 0.028316846592 m³, and square foot: 1 ft² = 0.09290304 m², both rounded here to 35.3146667 ft³ per m³ and 10.7639104 ft² per m², matching the Brickwork Calculator and Concrete Quantity Calculator.