Plaster Calculator
Estimates the cement, sand and water needed to plaster a wall from the area, thickness and mix ratio, including a wastage allowance.
Recent
Formula
How the calculation works
The tool first converts the plastered area and the coat thickness into a wet volume of mortar, which is the space the mixture must fill.
Because dry cement and sand bulk up when mixed, the wet volume is increased by a factor of about 1.33, and your wastage percentage is added on top of that.
Splitting the dry volume in the ratio of one part cement to n parts sand gives the cement volume, which is divided by the 0.0347 cubic metre bag to get the number of bags.
Common mistakes
- Forgetting that the bag volume is 0.0347 cubic metre, not the 50 kg weight, is a common error that throws off the whole cement estimate.
- Leaving out the wastage allowance understates the order, and plastering almost always loses some mortar to spillage and uneven surfaces.
When to use it
- Use it before buying materials so you order the right number of cement bags and sand volume for a plastering job.
- Use it to compare mix ratios and thicknesses and see how much each choice changes the cement and sand required.
Worked example
For 100 square feet at 12 mm thickness with a 1:4 mix and 10 percent wastage you need about 0.94 bags of cement, 4.6 cubic feet of sand and 24 litres of water.
Common questions
Why is the dry volume larger than the wet volume?
Dry cement and sand contain air gaps and expand in bulk, so the dry materials needed are about 1.33 times the wet mortar volume to fill the same space.
Related tools
-
Brick Calculator
Estimate how many bricks a wall needs from its length, height and thickness, allowing for mortar joints and wastage.
-
Building Material Estimator for Cement, Rod and Sand
Gives a quick estimate of cement bags, steel rods and sand needed for a given volume of concrete, using per-cubic-metre rates you can adjust.
-
Home Construction Cost Calculator (Bangladesh)
Multiplies floor area by the cost per square foot and the number of floors to estimate total building construction cost in Bangladesh.
-
House Rent and Advance Calculator
Adds the monthly rent and service charge and works out the advance you pay up front when renting a flat.
-
Land Registration Cost Calculator (Bangladesh)
Adds stamp duty, registration fee and source tax on a property value to estimate the total cost of registering a land deed in Bangladesh.
-
Land Unit Converter (Bangladesh)
Converts land area between the units used in Bangladesh, including square feet, square metres, katha, bigha, acre and decimal.
-
Plot Price Calculator
Find the total price of a plot from its size in katha or shotangsho and the rate per unit.
-
Roof Sheet Calculator
Find how many corrugated sheets are needed to cover a roof from its area, the sheet size and a wastage allowance.