Kanban Calculator
Calculate the whole containers and kanban cards your replenishment loop needs, with review time, a safety allowance and CSV sizing for many items.
Size the kanban loop
Calculations and CSV parsing run in your browser. Nothing is uploaded.
Kanban sizing result
| Kanban cards / containersceil(40 × (5 + 1) × (1 + 20 / 100) / 50) = 6 | 6 | ceil(40 × (5 + 1) × (1 + 20 / 100) / 50) = 6 |
|---|---|---|
| Demand during response time40 × 6 = 240 | 240 | 40 × 6 = 240 |
| Safety allowance before rounding240 × 20% = 48 | 48 | 240 × 20% = 48 |
| Total authorized loop inventory6 × 50 = 300 | 300 | 6 × 50 = 300 |
| Modeled maximum inventoryAll authorized containers full = total loop inventory | 300 | All authorized containers full = total loop inventory |
| Simple half-full-loop average300 / 2 = 150 | 150 | 300 / 2 = 150 |
The average assumes an even full-to-empty loop cycle. Measure actual warehouse on hand separately when stock is in process, in transit or held as safety stock.
Formula and worked example
Cards = ceil(D × (L + review time) × (1 + S / 100) ÷ C). D is average daily demand, L is replenishment lead time, S is the entered safety percentage, and C is container quantity. Cards round up to a whole container. Total loop inventory = cards × C. Modeled maximum = total loop inventory; the simple half-full-loop average = maximum ÷ 2.
At 40 units/day, 5 days replenishment plus 1 day collection, demand during response is 240 units. A 20% allowance adds 48. With 50 units/container, ceil(40 × 6 × 1.2 ÷ 50) = ceil(5.76) = 6 cards. Loop inventory and its modeled maximum are 300 units; the half-full-loop average is 150 units. These numbers are locked by a calculation test.
This model does not simulate arrivals, stockouts or the split between warehouse, transit and in-process inventory. Validate container handling, supplier reliability and the average-inventory assumption for your physical loop.
FAQ
What does the safety percentage mean?
It adds an allowance to demand during the replenishment response time. Enter 20 for 20%, not 0.2. It is a sizing factor, not a promised service level. Validate it against actual demand and replenishment variability.
Should review or collection time be included?
Yes, when cards wait for collection or an order-review run. This tool adds that delay to replenishment lead time before calculating demand and the safety allowance. Use consistent demand and lead-time days, such as both calendar days or both working days.
What do maximum and average inventory mean here?
Total authorized loop inventory and its modeled maximum are cards × container quantity, with every container full. The simple half-full-loop average is that maximum ÷ 2, assuming an even full-to-empty cycle. It is a planning illustration, not a prediction of average warehouse on hand: in-process stock, transit, retained safety stock and refill timing can change actual averages.
What happens with zero demand or invalid data?
Zero demand gives zero cards. Zero total response time also gives zero under this formula; check that assumption before using it. Container quantity must be greater than zero. Negative demand, times and safety percentages are refused. Bulk CSV is refused as a whole if any row is invalid or an item is duplicated.
Is my data uploaded?
No. Calculations and CSV parsing run in your browser, and the numbers and files you enter are never sent to a server, unless you choose to share a link, which carries the single-item inputs in its address. The page has no ads, sign-up or third-party trackers; the site host keeps standard anonymous visit counts.
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