What is the two-bin system?

A simple visual inventory management system that uses two bins per item to control the replenishment of small parts or materials without manual inventory tracking. The two-bin system is essentially a physical form of kanban: the empty bin serves as the signal.

How it works:
‍Thefirst bin contains the active stock used on a daily basis. The second bin contains a reserve quantity, calculated based on the item’s lead time. As soon as the first bin is empty, it is moved to a designated collection point or tagged with a kanban card to signal that it needs to be replenished. The employee switches to the second bin and continues working from it until the first bin is restocked and returned. The second bin then becomes the new active bin, and the cycle begins again.

Application and limitations:
‍Thesystem is ideally suited for low-cost, small items with relatively stable and predictable demand, such as fasteners, consumables, or standard parts. It aligns with the principles of just-in-time and pull: only what has actually been used is replenished.

For items with highly variable demand, long lead times, or high value, the two-bin system falls short. In such cases, more detailed kanban systems or other inventory management methods are recommended.

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