Flow / WORKSHEET 06

Kanban card quantity calculator

Size a basic withdrawal or production kanban loop. The result rounds up because a fractional card or container cannot cover demand.

Output: Required cards, covered units, base lead-time demand, and safety units.
Processing: In this browser only
Cost: Free · no account

LIVE WORKSHEET

Size the replenishment loop

Runs locally

Inputs and results stay in this browser. Verify important outputs independently.

APPLICATION NOTES

Use the result on the floor

Estimate kanban cards or containers from demand rate, replenishment lead time, safety factor, and container quantity. Keep the input boundary, unit definitions, and time period attached to any recorded result so another person can reproduce it.

Useful for

Set an initial supermarket card count.
Test lead-time reduction effects.
Review container sizing and working inventory.

MODEL BOUNDARY

Assumptions and limitations

Assumptions

Demand rate and lead-time unit are both days.
One card authorizes one standard container.
The safety percentage is applied to lead-time demand.

Limitations

The formula does not model demand distributions, service levels, minimum order quantities, seasonality, or capacity constraints.
Rounding can create more coverage than the exact calculation.

DECISION CHECK

Verify before changing the process

Pilot and monitor any kanban quantity before changing production controls. Too few cards can stop supply; too many can conceal defects and inflate inventory.

REFERENCE

Frequently asked questions

What formula does this use?

Cards equal demand rate times replenishment lead time times one plus the safety factor, divided by container quantity, rounded up.

Should safety always be added?

No fixed percentage is universally correct. Base it on observed variability and service needs, then improve the process rather than permanently padding inventory.