Separate ordered, delivered and used concrete quantities.
Which quantity should be compared with a supplier invoice?
Use the matching calculator
Use this decision sequence
- Record the geometric requirement and entered allowance as planned quantities.
- Record the supplier’s billable increment or minimum independently.
- Keep delivered quantity and unused material separate when those figures are available.
- Reconcile invoice arithmetic against the quote rather than silently treating every difference as calculation loss.
Keep the quantities distinct
| Quantity or assumption | How to use it |
|---|---|
| Planned requirement | Your measured quantity plus entered allowance. |
| Billable quantity | Determined by the supplied commercial terms. |
| Used quantity | An observed job record, not automatically equal to either of the first two. |
Worked comparison
An illustrative measured need of 1.03 m³ with a 0.25 m³ supplier increment becomes 1.25 m³ to order. If 1.1 m³ is recorded as used, the difference from the ordered quantity is 0.15 m³, while the difference from measured geometry is 0.07 m³. Those are different comparisons and do not independently diagnose a material yield problem.
Check before using the estimate
Delivery records and actual invoice terms are required to classify a discrepancy. This page does not judge concrete quality.
All dimensions, product properties, prices and specifications in this example are illustrative arithmetic inputs. Use the values from your measured plan, selected product data sheet and supplier quote. This guide does not choose construction specifications or certify safety.
Calculation and scope checked 2026-10-04. Methods and scope.
Related decisions
Deduct intersections in a supplied concrete rib grid
Why is the sum of two directions of ribs larger than the actual material?
Why a small depth error can dominate a volume estimate
Which measured dimension contributes the largest relative volume uncertainty?
Find an inch-to-foot thickness error before ordering
Why is a slab quantity twelve times larger than expected?
Choose component volumes over an unweighted average thickness
When does averaging several thicknesses misstate a concrete quantity?