Waste rate is comparable only when numerator and denominator follow a written definition. In ECR Retail Loss's 2026 survey, 29 retailers could not agree on a definition: some measure kilograms, others value, and some count donations as a success. With the same month and the same write-off record, a different denominator gives a different rate.
| Denominator | What it shows | When it fits |
|---|---|---|
| Net sales value | Most common use | Comparing categories |
| Purchase value | Supply side | Order quantity analysis |
| Units sold | Independent of price | Period tracking of one product |
Example: in one month waste is 18,000 TL, net sales 600,000 TL and purchases 450,000 TL; the rate is 3.0 percent on sales and 4.0 percent on purchases. If the same month has 2,400 units wasted and 40,000 sold, the unit rate is 6.0 percent. A high unit rate with a low value rate means cheap products cause the waste; the reverse points to a serious loss in an expensive category.
The total rate raises a warning and does not name the cause. Give the write-off record mutually exclusive reason codes such as spoilage, damage, loss and count difference; spoilage is a sub-cause of total waste and is never counted twice. Goods returned to the supplier or rejected at receiving go into a separate delivery record and stay out of store waste unless the written definition includes them.
Once temperature-related spoilage has its own code, the return on cold chain investment can be measured. State numerator, denominator, period, category and included causes in the report header; when the definition changes, recalculate earlier periods or mark the series as broken.
