Theoretical consumption is the material that should have been used for the work completed. It is calculated by multiplying the measured work quantity by a consumption coefficient: bags of cement per m³ of a concrete mix, kg of steel per BBS, or cement per m² of plaster.
The coefficients should come from your mix design, the contract or the specification you follow, not from a generic chart, because they change with mix, thickness and method. Steel quantities come from the bar bending schedule. Write down the coefficients you use so the same figures are applied every month.
Comparing theoretical with actual consumption is the heart of material reconciliation. A small, steady excess is normal wastage; a sudden jump means something to investigate. Check the work quantity first, because a measurement mistake is often the real cause. Then check the stock count and issue records.
Example
Illustrative: 100 m³ of concrete at an assumed 8 bags per m³ = 800 bags theoretical. If 860 bags were issued, the 60-bag excess needs explaining.
Material & inventory in CivilPilot
A material catalogue, requests from site, and stock for every project with every movement recorded.
