Rex says
Everyday utility math — the kind you'd otherwise pull up four browser tabs for. I keep it to one clean answer.
Try a scenario
Click to load — tweak from there.Inputs
Result
Kanban cards / bins needed
18
Total units circulating in the loop
900
Days of demand coverage
3.8
Exact pipeline quantity (before rounding)
900.0
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How to use this
- 1Enter average daily demand (units).
- 2Enter full replenishment lead time (days).
- 3Enter safety factor (buffer for variability) (%).
- 4Enter units per container/bin.
- 5Read your kanban cards / bins needed on the right — it updates as you type.
- 6Hit Share to keep the scenario or send it to someone.
About this calculator
A kanban system replenishes exactly what was consumed, and the number of cards (or bins) in the loop determines how much inventory circulates in that loop at any time — too few cards and you risk stockouts when replenishment lead time or demand spikes; too many and you're carrying unnecessary WIP that defeats the purpose of pull production. This calculator uses the standard kanban sizing formula: average daily demand times replenishment lead time (in days) gives the base pipeline quantity, then a safety factor is added to buffer against demand variability and supplier reliability, and the whole thing is divided by container/bin size to get the number of cards or bins needed. Lead time here should include the full loop — production or supplier lead time plus any queue, transport, and processing time before the container returns to the point of use, since kanban has to cover the complete replenishment cycle, not just production time.
Worked example
Using the values the calculator loads with:
Inputs
- Average daily demand: 240 units
- Full replenishment lead time: 3 days
- Safety factor (buffer for variability): 25 %
- Units per container/bin: 50
Results
- Kanban cards / bins needed: 18
- Total units circulating in the loop: 900
- Days of demand coverage: 3.8
- Exact pipeline quantity (before rounding): 900
What each field means
Inputs
- Average daily demand (units)
- The average daily demand used in the calculation, measured in units. Starts at 240 units so you have a working example on load.
- Full replenishment lead time (days)
- The full replenishment lead time used in the calculation, measured in days. Starts at 3 days so you have a working example on load.
- Safety factor (buffer for variability) (%)
- The safety factor (buffer for variability) used in the calculation, measured in %. Starts at 25 % so you have a working example on load. Accepted range: 0–200 %.
- Units per container/bin
- The units per container/bin used in the calculation. Starts at 50 so you have a working example on load.
Results
- Kanban cards / bins needed
- Returned as a whole number and shown as the headline result. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Total units circulating in the loop
- Returned as a whole number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Days of demand coverage
- Returned as a decimal number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Exact pipeline quantity (before rounding)
- Returned as a decimal number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
FAQ
What safety factor should I use?
20-30% is a common starting point for stable, well-understood processes with reliable suppliers. Increase it toward 50-100% for volatile demand, unreliable supplier lead times, or a new kanban loop where you don't yet have confidence in the process — you can tighten it later once you have real performance data.
What lead time should I use if the supplier ships weekly?
Use the full cycle from when a card is triggered to when replenished stock is available and usable at the point of use — including any batching delay (average half the shipping cycle if orders are batched weekly), transit time, receiving/put-away time, and any incoming inspection. Underestimating lead time is the most common kanban sizing mistake.
How does container size affect card count?
Smaller containers require more cards to hold the same total pipeline quantity, but they also mean smaller replenishment triggers and tighter WIP control, which is usually preferred in lean systems. Very large containers reduce card count but can hide problems and slow response to demand changes — most lean practitioners favor smaller containers even though it means managing more cards.
Should I recalculate kanban sizing regularly?
Yes — review it whenever demand shifts materially or lead time changes (new supplier, process change), typically on a quarterly cadence at minimum. A kanban loop sized for last year's demand pattern will either starve the line or build excess WIP if conditions have changed.
Accuracy and limitations
- Estimates assume standard, average conditions — local rules, pricing, and materials vary.
- Results are rounded for readability; add a buffer before ordering, booking, or committing.
- Double-check anything with a real cost attached against a local quote.
Related tools
Cite this calculator
Writing about this topic? Grab a citation — every link helps keep these tools free.
RevenueLab. (2026). Kanban Card Count Calculator. Retrieved from https://www.revenuelab.fyi/toolbox/kanban-card-count
<p>Source: <a href="https://www.revenuelab.fyi/toolbox/kanban-card-count" target="_blank" rel="noopener">Kanban Card Count Calculator — RevenueLab</a> (2026).</p>
Source: [Kanban Card Count Calculator — RevenueLab](https://www.revenuelab.fyi/toolbox/kanban-card-count) (2026).