Direct comparison
Cost-Per-Use vs. Cost-Per-Unit
Why unit price alone misleads supply budgeting: a worked example of a cheaper item costing more per successful use once failure rate is counted.
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How do Cost-Per-Unit, Cost-Per-Use compare side by side?
The table below compares Cost-Per-Unit, Cost-Per-Use across 9 procurement-relevant dimensions, from what it measures through relationship to total cost of ownership (tco).
Side-by-side comparison
| Dimension | Cost-Per-Unit | Cost-Per-Use |
|---|---|---|
| What it measures | The purchase price of a single item, as it appears on an invoice or catalog listing. | The fully-loaded cost of one successful use — item cost divided by the number of times it actually accomplishes its purpose without failure, waste, or rework. |
| Formula | Unit price (or case price ÷ units per case). | Unit price ÷ first-pass success rate (successful uses ÷ units consumed, including discarded or failed units). |
| What it captures | Only the acquisition price of the item. | Acquisition price plus the effect of defect rate, waste rate, and rework tied directly to using the item. |
| What it deliberately excludes | Failure rate, waste, rework, and any use-associated cost beyond the sticker price. | Costs unrelated to the item itself — general facility overhead, staff time that would be spent regardless of which product is used. That's the territory of a full Total Cost of Ownership analysis for capital equipment, not this metric. |
| Best for comparing | Identical or near-identical items from different vendors at the same known failure/waste profile — a genuine apples-to-apples price check. | Consumables where the products being compared have materially different failure, defect, waste, or rework rates — which is most real substitution decisions. |
| Time horizon | None — a single transaction price, true at the moment of purchase. | A representative usage period (a month, a quarter, a defined lot) long enough that the observed failure/waste rate is stable, not a fluke of a small sample. |
| Data required | The invoice or catalog price. Nothing else. | Unit price plus a measured or vendor-reported first-pass success rate for that specific use case — generic manufacturer defect specs aren't a substitute for how the item performs in your facility's actual workflow. |
| Main risk of using it alone | Selecting the item with the lower sticker price that, once failed/wasted units are counted, actually costs more per successful use. | Spending tracking effort on low-value, low-variability items where unit price alone was already a reliable enough proxy. |
| Relationship to Total Cost of Ownership (TCO) | — | The same “don't stop at sticker price” logic TCO applies to capital equipment over a multi-year ownership horizon, applied instead to a single consumable item over its use cycle. See the Total Cost of Ownership (TCO) dictionary entry for the equipment-level version of this idea. |
Common questions
Common questions about Cost-Per-Unit vs Cost-Per-Use
Can you show a worked example of cost-per-unit giving the wrong answer?
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Illustrative composite, not real vendor pricing — use it as a template, not a sourced quote. A facility is choosing between two single-use consumables for the same formulary slot. Product A is priced at $0.80/unit; on this facility's own usage data, 20% of units are discarded before or during use (sterile-field breach, packaging defect, or in-use failure) and a replacement unit has to be opened to complete the same procedure, so the first-pass success rate is 80%. Product B is priced at $0.95/unit with a 97% first-pass success rate. On unit price alone, A looks $0.15 cheaper. Cost-per-use tells a different story: A is $0.80 ÷ 0.80 = $1.00 per successful use; B is $0.95 ÷ 0.97 ≈ $0.98 per successful use. B is the cheaper option once failure is counted, despite costing more per unit — at 10,000 procedures a year that's roughly $200 in B's favor, before even counting the staff time each failed-and-reopened unit costs with A.
When is cost-per-unit alone good enough?
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When you have solid reason to believe the failure/waste rate is essentially identical across the options being compared — for example, two lots of the exact same SKU from the same manufacturer, or two items with a long track record at your facility showing no meaningful difference in first-pass success. In that case the lower unit price is genuinely the lower cost, and calculating cost-per-use adds precision without changing the decision.
How do you get a first-pass success rate if you don't already track one?
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Start with a defined sample: pull a representative lot or a fixed time window (a month is usually enough for a moderate-volume item) and have staff log every unit that's opened but not successfully used — packaging defect on opening, in-use failure, contamination, or any reason a second unit had to be opened to complete the same task. Successful uses ÷ total units opened in that window is your first-pass success rate. It doesn't need to be perfect to be useful; even a rough estimate from a two-week sample is enough to catch a failure-rate gap large enough to reverse a unit-price ranking.
Does cost-per-use include staff labor?
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Only the labor directly tied to redoing a failed attempt — the extra time to open, prep, and use a replacement unit after a failure. It does not include the baseline staff time the procedure would take regardless of which product is used; that's a real cost, but it's identical across the options being compared and doesn't change the ranking, so most cost-per-use calculations leave it out to keep the comparison focused on what actually differs between the products.
Going deeper
