Kanban Card Quantity Calculator

Work out kanban card quantity instantly with clear inputs, formula shown and shareable results.

About Kanban Card Quantity Calculator

Kanban card count is demand during lead time, uplifted for variability, divided by container size and rounded up. Each card authorises one container, so the card count is a hard cap on work-in-process: maximum inventory is cards x container quantity.

Formulas

Kanban cards

Cards = ceil(daily demand x lead time x (1 + safety allowance) / container size)

Inventory cap

Maximum inventory = cards x container quantity

Worked example

With the default values below, Kanban Card Quantity Calculator returns Kanban Cards Required of 15. Change any input above and every figure here is recalculated in your browser.

Inputs used

Average Daily Demandminimum 0.01 units/day: 800 units/day
Replenishment Lead Timeminimum 0.01 days: 1.5 days
Container Quantityminimum 1 units: 100 units
Safety Allowanceaccepts 0–100 %: 20 %

Results

Kanban Cards Required: 15
Unrounded Card Count: 14.400
Maximum System Inventory: 1,500
Days Of Cover: 1.875

Step by step

1Values used
2Kanban cards
3Inventory cap
4Kanban Cards Required= 15
5Unrounded Card Count= 14.400
6Maximum System Inventory= 1,500
7Days Of Cover= 1.875

Assumptions and limits

The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 3 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

How do I reduce inventory in a kanban system?

Remove a card. That forces lead time or container size down; if the line starves, the underlying constraint is exposed and can be fixed. This is the deliberate mechanism of continuous improvement in pull systems.

What safety allowance is appropriate?

10-20% for stable internal loops with reliable supply, 30-50% for external suppliers or variable demand. Excessive allowance defeats the purpose of the pull system.