Cement Calculator: How Many Bags for Concrete, Plaster or Brickwork?
Pick the type of work, enter the volume or area and the mix, and see the cement in 50 kg bags. The tool also shows the weight and the sand that goes with it.
Estimates only. Check important results before you rely on them.
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From related categoriesHow to use this calculator
- Choose concrete, plaster or brickwork.
- Enter the volume (concrete, brickwork) or the area and thickness (plaster).
- Pick the mix or ratio and the wastage.
- Read the bags of cement. The result is rounded up so you do not run short.
The formula
Worked example
1 m³ of M20 concrete with 5% wastage needs about 8.5 bags, so order 9. For 500 sq ft of 12 mm plaster in a 1:4 mix, the wet volume with wastage is 0.585 m³, which needs about 4.5 bags of cement.
Understanding your result
The result is rounded up to whole bags. The "Sand for the same work" line saves a second calculation. If your site has uneven walls the plaster thickness will be higher, so measure a sample wall.
When to use it
- Order cement for a slab, plinth or column.
- Estimate plastering cement for a house.
- Plan mortar for a block or brick wall.
In-depth guide
Cement needed per cubic metre of concrete
The table uses the method on this page: a dry volume factor of 1.54, 5% wastage and a 50 kg bag of 0.0347 m³. Values are for 1 m³ of finished concrete.
| Grade | Mix (cement : sand : stone) | Bags (50 kg) | Order |
|---|---|---|---|
| M10 | 1 : 3 : 6 | 4.7 | 5 |
| M15 | 1 : 2 : 4 | 6.7 | 7 |
| M20 | 1 : 1.5 : 3 | 8.5 | 9 |
| M25 | 1 : 1 : 2 | 11.6 | 12 |
Where each grade is used
- M10 and M15: levelling and base layers, simple flooring and non-structural work.
- M20: common choice for beams, slabs, columns and footings in ordinary houses.
- M25 and above: heavier loads or exposure, as your structural engineer specifies.
Cement for plaster and masonry
Plaster volume is area times thickness. A 12 mm coat on 500 sq ft is about 0.557 m³ before wastage. Because sand bulks and shrinks, the dry material is more than the wet volume, which is why the calculator applies a dry factor of 1.33 for plaster and 1.27 for mortar. Brick mortar is taken as about 25% of the brickwork volume. For a detailed brick count use the Brick Calculator.
How to avoid wastage and shortfall
- Order a full bag more than the estimate when the number sits just above a whole bag.
- Store cement off the ground, away from moisture, and use older stock first.
- Measure sand and stone by volume boxes rather than by shovels.
- Keep the water-cement ratio your engineer specifies. Extra water weakens concrete.
- Have the contractor confirm the mix and quantity before you place the order.
Limits of the estimate
Real consumption depends on the quality of sand, the stone size, site conditions and workmanship. Treat the figure as a planning number and confirm it with your engineer or contractor.
Assumptions and limits
These are planning estimates. Real use depends on material quality, site conditions and workmanship. Confirm quantities with your engineer or contractor before ordering. The mortar share of brickwork (25%) varies with brick size and joint thickness. Use the Brick Calculator for a detailed estimate.
Frequently asked questions
How many cement bags are needed per square foot of plaster?
For 12 mm of 1:4 plaster, about 0.009 bags per sq ft, or roughly 9 bags per 1,000 sq ft.
How much cement is in a bag?
A standard Indian cement bag is 50 kg, which is about 0.0347 m³.
What mix is used for plaster?
1:4 is common for internal walls and 1:3 or 1:4 for external plaster, depending on the specification.
Does the result include wastage?
Yes. It adds the wastage percentage you enter to the volume.
Should I round up the number of bags?
Yes. The headline figure is already rounded up.