Written and maintained by CASRAI Editorial Board
Last updated
Short answer
Kanban inventory is a pull-based way of restocking supplies: a physical or electronic signal, such as an empty bin, a card or a computer order, tells staff that more of an item is needed, and only then is more supplied. In the two-bin form used for consumables, each item sits in two bins and the emptied front bin is the reorder signal.
Definition and scope
The US Environmental Protection Agency describes a kanban as “a card, labeled container, computer order, or other device used to signal that more products or parts are needed” from the previous step in a process. The word means card or sign in Japanese. EPA contrasts this pull approach with traditional push methods, which are “based on an estimated number of expected sales”, and lists three kinds of kanban: supplier kanban (orders to outside suppliers), in-factory kanban (between processes) and production kanban (operating instructions within a line).
Supplier kanban is the kind that matters for laboratory and clinical supply rooms, where the “customer” is a bench or a care unit and the “supplier” is a stockroom or an outside vendor. The same idea appears briefly in CASRAI’s guide to the lean laboratory, where kanban is one of several lean methods.
How the two-bin system works in practice
Owens & Minor, a hospital supplier, describes the two-bin method in an article by its supply chain solutions director dated October 5, 2023 (supplier-authored, so read it as one operator’s account):
- Two bins sit on a rack, one behind the other, each holding the desired quantity of one item.
- Staff use the front bin.
- When the front bin is empty it is placed on top of the rack and the full bin is moved forward. In the article’s words, the empty bins on top of the racks “serve as a visual signal that it’s time to replenish that item.”
- The second bin acts as a safety stock until materials management staff replenish the item, which the article describes as happening on rounds.
The article credits first-in, first-out use of stock with lowering the risk that items go unused and expire, and says the equipment investment is minimal: racks and bins. Vendor BlueBin’s kanban page describes the same layout (two bins per supply item at the point of use) and adds that the replenishment signal can be a barcode scan or a kanban card.
Two-bin kanban versus a single signal card
The EPA definition shows why a bin and a card are the same idea. What matters is that the signal travels with the stock and triggers supply only when stock has been withdrawn. EPA’s second rule is that “the upstream processes only produce what has been withdrawn.” In a supply room, that means replenishment follows consumption rather than a forecast.
Kanban versus periodic automatic replenishment (PAR)
The Owens & Minor article presents the bins in the context of periodic automatic replenishment (PAR) levels: it raises the labor needed to count stock across hundreds of locations as the difficulty, and presents the two-bin method as an approach that does not depend on counting every location. It does not say how bin quantity is set or how often rounds happen.
| Approach | What triggers resupply | Source |
|---|---|---|
| Kanban (two-bin) | A visual signal: the front bin is empty | Owens & Minor; EPA definition of a kanban signal |
| PAR level | A count of stock against a target level | Owens & Minor (counting burden); CASRAI term par level |
| Push / forecast ordering | An estimate of expected demand | EPA |
Where it matters for labs, clinics and supply decisions
Owens & Minor positions two-bin kanban for low-cost, high-volume consumables, naming tubing, syringes, needles and adhesives, and gives a 30 ml syringe as its example. Because replenishment depends on someone seeing the empty bin, the method needs a person or process that collects the signal. Where an outside distributor handles that, see CASRAI’s term on vendor-managed inventory. For the par and reorder questions that arise in wound-care purchasing, see the guide to wound-care supply wholesale buying, and for stock that ages out, deadstock and obsolete medical supply inventory.
Checklist: what to ask before relying on published savings claims
- Who wrote the claim? Published material on two-bin systems largely comes from suppliers and vendors, so treat its figures as one party’s account.
- Is a sample, period or method stated for the percentage? Vendor pages often give averages without one, and a single page can give differing figures for the same measure.
- Does the source say how bin quantity and round frequency were set? The Owens & Minor article does not, so these are local decisions to document.
- Does the item suit the method? The source examples are low-cost, high-volume consumables.
Common misunderstandings
- “Kanban is a software product.” EPA’s definition includes a card, a labeled container or a computer order. Software is one form of the signal, not the definition.
- “The second bin is extra stock to ignore.” The source describes it as a safety stock held until replenishment arrives.
- “Once set, bin quantities stay fixed.” EPA’s rule is that the number of kanban “should be decreased over time”, as a way to uncover areas needing improvement. EPA also warns that JIT and kanban may not succeed where market fluctuations are large or unpredictable.
FAQ
What is a two-bin kanban?
A two-bin kanban holds each item in two bins, one behind the other. When the front bin empties, it becomes the signal to reorder while the second bin supplies the item until stock arrives.
What does periodic automatic replenishment mean?
Owens & Minor uses “periodic automatic replenishment (PAR) levels” for count-based restocking toward a target quantity. See the CASRAI term on par level for the calculation inputs.
Is a two-bin system the same as kanban?
The two-bin system is one way to apply a kanban signal. EPA’s definition is broader and includes cards and computer orders.
Sources
- US EPA, “Lean Thinking and Methods: JIT/Kanban”, https://www.epa.gov/sustainability/lean-thinking-and-methods-jitkanban (checked 2026-10-30).
- Owens & Minor, “Kanban: a simple, effective solution to consumable supply management in the hospital”, https://www.owens-minor.com/insights/kanban-a-simple-effective-solution-to-consumable-supply-management-in-the-hospital/ (dated October 5, 2023; read 2026-10-30; supplier-authored).
- BlueBin, “Kanban”, https://bluebin.com/solutions/kanban/ (vendor page; read 2026-10-30; used only for the two-bin layout and scan or card signal).
