Cement Calculator
Home & ConstructionWork out how many cement bags a concrete pour or a plastering job needs, with sand and aggregate.
Runs entirely in your browser — nothing is uploaded
Features
- Concrete and plaster modes with standard mixes.
- Bags, kilograms and cost.
- Sand and aggregate quantities alongside.
- Uses the 1.54 dry volume factor rather than the wet volume.
- Runs in your browser.
How to use the Cement Calculator
- 1Choose whether you are pouring concrete or plastering.
- 2Enter the dimensions and pick the mix ratio.
- 3Read the bag count and order against it.
Frequently asked questions
How many cement bags are in a cubic metre of concrete?
For M20 at 1:1.5:3, about 8 bags per cubic metre of finished concrete. For M15 it is around 6.5, and for M25 around 11. Those figures already include the 1.54 dry volume factor.
What is the 1.54 factor?
Dry cement, sand and aggregate lose about a third of their bulk once mixed with water and compacted, because the finer material fills the gaps between the coarse. Ordering against the wet volume is the classic way to end up a third short.
How long does cement keep?
About three months in the bag. It absorbs moisture from the air and loses strength, so order what the job needs rather than stockpiling. Store bags off the floor, away from external walls, and use the oldest first.