How this calculation works
Estimate the wet volume for identical rectangular pours, including an explicit waste allowance. The cement, sand and aggregate figures are a separate nominal ingredient estimate using fixed assumptions. They do not select a structural concrete grade or replace a supplier mix design; the wet volume is the relevant starting point when discussing a ready-mix order.
Worked example
This example uses illustrative inputs. Your current result is shown above.
One pour 5 m long, 4 m wide and 0.10 m deep has geometric volume 2 m³. With 5% waste, wet volume is 2.1 m³ and nominal dry volume is 3.234 m³. The fixed mix assumptions give 17 whole 50 kg cement bags, 0.882 m³ sand and 1.764 m³ aggregate.
Assumptions and limits
- Dimensions are metres and quantity repeats the same rectangular pour. Depth is entered in metres, not centimetres.
- Dry-volume factor 1.54, bulk cement density 1,440 kg/m³ and proportions 1:1.5:3 are fixed estimating assumptions; water, moisture, compaction and strength design are not calculated.
Questions people ask
Should I order wet or dry volume from a ready-mix supplier?
Discuss the required placed wet volume and allowance with the supplier. The dry-volume estimate is for nominal ingredient quantities, not an additional concrete order.
Does this certify a concrete grade?
No. Material testing, structural requirements, exposure conditions and an approved mix design determine suitability. The calculator only estimates quantities under its stated proportions.