TryBuildCalc12mm Gypsum Plaster Calculator (Standard Single-Coat Wall Thickness)
Estimate materials for 12mm gypsum plaster.
🕒 Last updated: August 25, 2026
Inputs
ℹ️Typical: 10-15 mm (wall, usually a single coat), 6-10 mm (ceiling)
ℹ️Check your product's technical data sheet — typical range is 0.8-1.1 kg/m²/mm for gypsum/POP plaster.
ℹ️Check your product's label — common gypsum/POP plaster packs are 25, 40, and 50 kg.
Cost
For 9.29 m² of plaster area at 12 mm thickness, you need approximately 5 gypsum plaster bags (25 kg each).
Plaster Volume
Plaster area: 9.29 m²
Applied volume: 0.1115 m³
Coverage rate: 0.90 kg/m²/mm
Powder Required
Theoretical: 100.3 kg
With 10.0% wastage: 110.4 kg
Order Summary — Theoretical vs. Order Quantity
| Bags | Theoretical | Order Quantity |
|---|---|---|
| Gypsum/POP plaster | 4.0 bags | 5 bags (whole) |
Theoretical = before wastage. Order Quantity = after your 10.0% wastage allowance, rounded up to a whole bag.
Assumptions Used
No dry-volume correction applied — gypsum/POP plaster is a pre-mixed powder (water only, no site-mixed sand). Wastage applied once to the final powder weight before bag rounding.
Need traditional cement and sand plaster instead? Plaster Calculator →
Painting this wall once the plaster has fully dried? Paint Calculator →
Looking for the verification checklist, reference tables, tips, or common mistakes?See the complete Gypsum / POP Plaster Calculator.
12mm gypsum plaster material estimate
12mm is a common single-coat thickness for internal gypsum/POP wall plaster — this page is pre-selected to that thickness.
Edit the wall dimensions or coverage rate above and the material breakdown and worked example update from the active values, still using 12mm thickness.
- 12mm typically needs about 10.8 kg of powder per m² at a 0.9 kg/m²/mm coverage rate.
- A common single-coat thickness for internal walls where gypsum plaster replaces both backing and finish coats.
- Always confirm the maximum single-coat thickness on your product's technical data sheet.
Gypsum Plaster Formula: How Is Powder Quantity Calculated?
Gypsum/POP plaster quantity is calculated from the plastered area, coat thickness, and the product's coverage rate — unlike cement-sand plaster, there is no dry-volume correction step, since the powder is a single pre-mixed material rather than raw ingredients combined on site.
Step 1 — Plaster Area & Applied Volume
Plaster Area = Wall Length × Wall Height
Applied Volume = Plaster Area × Plaster Thickness
Plaster area is the total surface to be plastered — internal wall, external wall (where suitable), or ceiling. Applied volume is the actual plaster volume needed to cover that area at the specified coat thickness.
Step 2 — Powder Weight from Coverage Rate
Powder Required (kg) = Plaster Area (m²) × Thickness (mm) × Coverage Rate (kg/m²/mm)
Coverage rate is published by the manufacturer on the product's technical data sheet, typically 0.8-1.1 kg of powder per m² per mm of thickness. This single step replaces the dry-volume correction and mix-ratio split used for cement-sand plaster, since gypsum plaster is bought pre-mixed.
Step 3 — Wastage & Bag Conversion
Final Powder (kg) = Powder Required × (1 + Wastage %)
Bags = ROUND UP(Final Powder ÷ Bag Size)
Wastage is applied to the theoretical powder weight for the practical order quantity, then converted into whole bags using the selected bag size (commonly 25, 40, or 50 kg) — you can't buy a fraction of a bag.
Worked Example
This example walks through your current inputs above, using the same steps as the Formula section.
Input Values Used
| Input | Value | Why it is used |
|---|---|---|
| Length × height | 10ft × 10ft | Sets the plaster surface area |
| Thickness / coverage rate | 12mm, 0.9 kg/m²/mm | Sets applied volume and powder weight |
| Wastage / bag size | 10%, 25 kg | Sets order quantity and bag count |
Step 1 — Area & Powder Weight
| Calculation | Substitution | Result |
|---|---|---|
| Plaster area | 10ft × 10ft | 9.29 m² |
| Applied volume | 9.29 × 12mm | 0.1115 m³ |
| Powder required (theoretical) | 9.29 × 12 × 0.9 | 100.3 kg |
Step 2 — Wastage & Bags
| Material | Theoretical | Order Quantity |
|---|---|---|
| Gypsum/POP plaster | 4.0 bags | 5 bags (whole) |
Therefore, for 9.29 m² of plaster at 12mm thickness, you need approximately 5 gypsum/POP plaster bags (25 kg each).
Related Calculators
Disclaimer: This calculator provides approximate results for planning and estimation purposes only. Actual requirements may vary based on site conditions, materials, workmanship, and local building regulations. Always consult a qualified engineer, architect, or construction professional before making final decisions.