Kanban is a pull system. Instead of pushing stock in according to a forecast, you replenish only when stock is actually consumed, triggered by a signal. Developed by Taiichi Ohno at Toyota, it is one of the cleanest ways to keep buffers small without flying blind, and it works well beyond the factory floor.
How a kanban inventory system works
The mechanism is a signal that travels backward through the chain when stock is used:
- Each item has a defined bin or container with a kanban card (physical or digital).
- When the bin empties or hits its trigger level, the card is released, signalling replenishment.
- That signal authorises a refill from the upstream source, of a fixed, pre-agreed quantity.
- The refill arrives, the card resets, and the loop repeats.
Nothing moves until consumption pulls it. That is the difference from forecast-driven replenishment: kanban reacts to real demand, so it self-corrects as demand shifts instead of waiting for the next forecast cycle.
The benefits
- Smaller buffers. Because replenishment tracks actual use, you hold less safety stock for the same availability.
- Visual and simple. An empty bin is an unambiguous signal. The floor can run it without constant management attention.
- Self-throttling. When demand slows, fewer cards release, so stock does not pile up. When demand rises, cards release faster.
- Fewer stockouts on steady items. For predictable, regularly consumed SKUs, the loop is very reliable.
Where kanban fits, and where it does not
Kanban shines on items with steady, repeating demand and reliable supply. It is a natural partner to just-in-time thinking. It struggles with lumpy or one-off demand, long and unreliable lead times, or items that change often, because the fixed loop assumes a stable pattern. Many operations run kanban on their steady core and a forecast-driven rule on the volatile tail.
Setting it up
Size each loop deliberately: the trigger level and refill quantity should cover demand over the replenishment lead time plus a small buffer. Start with your steady, high-turn items where the payoff is clearest, measure the result, then extend. As with every method, kanban depends on an accurate stock picture underneath it, which is the job of inventory control.