Plaster calculator
How much dry mix a wall needs at a given layer thickness.
Fill in the fields and the result will appear here automatically.
Calculates dry mix from wall area, layer thickness and your consumption per 1 mm. Enter area directly or derive it from length and height. The default 8.5 is a hypothetical user consumption, not a typical gypsum-plaster rate: a manufacturer value for a 10 mm layer must first be divided by 10.
How it works
Formula and logic
A = length·height or supplied area; mass = A·t·c, with A in m², t in mm and c in kg/m²/mm. Bags = ⌈mass/bag mass⌉; consumption per m² = t·c. Active dimensions, thickness, consumption and bag mass are positive and finite. Upward bag rounding uses decimal values without deleting a small positive remainder.
Example
With the retained hypothetical c = 8.5 kg/m²/mm, 20 m² at 10 mm gives 1700 kg and 57 bags of 30 kg. This is not the KNAUF Rotband rate. Its stated approximate 8.5 kg/m² at 10 mm means c = 0.85, giving 170 kg and 6 such bags, estimated from that stated consumption.
Fields and units
- How to give the area — list option
- Wall area — m²
- Wall length — m
- Wall height — m
- Layer thickness — mm
- Consumption — kg/m²/mm
- Bag weight — kg
How to use
- — Choose supplied area or positive wall length and height.
- — Enter thickness in mm and convert the packaging consumption specifically to 1 mm.
- — Enter bag mass; account for openings, reveals and chosen allowance in the area or a separate budget.
Method and limitations
- Calculation method
- Formula and logic
- Data or methodology source
- KNAUF Rotband: about 8.5 kg/m² at 10 mm, illustrating 0.85 kg/m²/mm
- Limitation
- The default 8.5 is a hypothetical user consumption, not a typical gypsum-plaster rate: a manufacturer value for a 10 mm layer must first be divided by 10.
FAQ
Where does the consumption figure come from?
Use the specific product instructions and the thickness to which the figure applies. If c₀ kg/m² is given for t₀ mm, enter c₀/t₀.
Why is 8.5 at 10 mm different from 8.5 per 1 mm?
The unit basis differs by a factor of ten. This field requires consumption per 1 mm. The retained 8.5 is hypothetical; the calculator neither selects a product nor corrects it automatically.
How should I choose layer thickness?
Use measurements and the selected product limits. Averaging the smallest and largest gap does not guarantee the area-weighted mean thickness.
Are openings and reveals included?
Not automatically. Subtract opening areas and add reveals; primer, reinforcement and process losses are not separately calculated.