Kanban card calculator
Enter the demand, the replenishment time, the safety margin and the units per container: it tells you how many cards are needed.
Units in circulation
55.0
Kanban cards
3
Cards = demand × replenishment time × (1 + safety) ÷ units per container, rounded up. Replenishment time includes manufacturing, transport and waiting time for a container. The preloaded values are an illustrative example.
How it works
You enter the demand per unit of time, the replenishment time (in the same unit of time), the safety margin as a percentage and the units that fit in each container.
- Units in circulation = demand × replenishment time × (1 + safety).
- Cards = units in circulation ÷ units per container, rounded up.
This is the formula for sizing kanban supermarkets (Minitab Engage, based on Monden). Replenishment time includes everything that happens from the moment the card is released until the full container comes back: production, transport and waiting. Preloaded: with 100 units per hour, 0.5 hours of replenishment, 10% safety and containers of 25 units, 3 cards are needed. Note: with fewer cards there are shortages; with more, excess inventory. It is best to reduce them little by little and watch which problem appears.
Sources
These are the ones from the article where the theory behind this tool is developed.
How does a card system work and what variants are there? It is in the article Kanban: cards, containers and how many are needed.