Kanban Card Size Calculator (Number of Kanbans and Container Quantity)
Kanban only works when the number of cards is right. Too few starve the line, too many bring back the inventory you were trying to remove. This calculator applies the classic formula, rounds up to whole cards and shows the maximum inventory and days of cover.
Your numbers
Time from card release to material back at the point of use, including waiting and transport.
Policy factor to cover variability. Keep it low and reduce it over time.
Fixed quantity per container or card.
Your results
Classic formula: kanbans equal demand times lead time times (1 plus safety factor), divided by container quantity. Container size should also respect packaging, handling and ergonomics.
Number of kanbans vs replenishment lead time
Sweeps Replenishment lead time from 0.5 to 10, holding your other inputs fixed.
Size kanban loops from ERP data at scale
Optional: we can calculate kanban quantities for many parts using your demand and lead time history.
Optional. The tool and every export work without this. No spam.
How to use the calculator
Enter the average daily demand for the part and the replenishment lead time, which covers everything from the empty card being released to full material arriving at the point of use. Choose a safety factor that reflects variability in demand and supply; twenty percent is a common starting point but not a rule. Enter the container quantity, chosen first for handling and packaging reasons. The tool returns the number of cards, maximum inventory and days of cover.
- Use realistic demand, such as average of the last 8 to 13 weeks
- Measure actual lead time including queues and transport
- Choose container size by handling and ergonomics first
- Review the card count quarterly when demand changes
The formula
The number of kanbans equals demand per day times lead time in days times one plus the safety factor, divided by the container quantity, rounded up. The result is also the number of full containers that can exist in the loop at once, so maximum inventory equals cards times container quantity. In the sample, 240 pieces per day, a 1.5 day lead time and 20 percent safety give 432 pieces needed, which is eight containers of 60. The chart shows the cards required as the lead time rises, which is the strongest argument for shortening replenishment time.
Practical use and ERP notes
Most ERPs can run kanban natively, including SAP PP kanban control cycles, Oracle kanban replenishment and Infor SyteLine or LN pull signals, but the count of cards still has to come from analysis like this. Put the result into the control cycle or supply area configuration and review it with the line. If the card count must change often, treat that as a signal that demand or lead time is unstable.
Common mistakes
Setting the safety factor high to hide problems, using planned lead time rather than actual, choosing very large containers to cut moves and then wondering why inventory rises, and failing to remove cards when demand falls. Also remember that kanban suits stable, repetitive demand; for lumpy or low-volume items other methods such as min-max may suit better.
Frequently Asked Questions
What is the kanban formula?
Number of kanbans equals daily demand times replenishment lead time times one plus the safety factor, divided by the container quantity, rounded up to a whole number.
How do I pick the container quantity?
Pick a quantity that suits handling, packaging and ergonomics, and that gives a reasonable number of cards. Very small containers create many moves; very large ones create inventory.
What safety factor should I use?
Start with what variation requires, often 10 to 30 percent, and reduce it as you stabilize demand and supply. A high factor hides problems that kanban is supposed to expose.
Does kanban work for low-volume parts?
Usually less well. For irregular or very low demand, a reorder point or make-to-order approach may be better. Kanban is strongest for stable, repetitive parts.
If you want kanban quantities recalculated regularly from ERP demand and lead time data, with approval before updates, we can help set that up.
Related Tools
SAP PP Kanban Quantity and Container Calculator
Size an SAP kanban control cycle: how many kanbans of what quantity cover demand during replenishment, plus the maximum inventory they imply.
OracleOracle Fusion Kanban Card Calculator
Size a kanban loop: how many cards or containers you need for a given demand, replenishment time, container quantity and safety factor.
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Compute the takt time your line must hit to meet customer demand, plus the required hourly rate for supervisors and schedulers.
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Fill in the data box for each process step of your current-state map and get total lead time, value-added time and process cycle efficiency.
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