Kanban sizing calculator
Estimate a starting number of Kanban signals or containers for one item in one replenishment loop, with every part of the calculation shown.
Average units consumed per selected time unit.
Elapsed replenishment time in the same selected unit.
Whole units represented by one signal/container.
Explicit additional percentage; 10 means add 10%.
Exact container requirement: 3.3 · rounded up to a whole container
- Demand during replenishment
- 240 units
- Safety buffer units
- 24 units
- Buffered requirement
- 264 units
- Units represented after rounding
- 320 units
- Rounding surplus
- 56 units
What the represented quantity contains
Base replenishment demand, the entered safety buffer and the surplus created by rounding up to whole containers.
Use this as a starting quantity to validate against actual variation, service expectations and loop behavior. It is not a stockout guarantee.
Included
- Average demand during one replenishment lead time
- An explicit user-entered safety buffer percentage
- One signal representing one fixed-quantity container
- Exact requirement and conservative rounding up to whole containers
Not included
- Demand distributions, service levels or a stockout guarantee
- Multiple items, loops, suppliers or container sizes
- Minimum order quantities, scrap, downtime or transport constraints
- ERP integration, simulation or automatic safety-buffer policy
What this means
This simple planning model starts with average demand during replenishment: average consumption rate multiplied by replenishment lead time. The selected time unit changes only how those two inputs are displayed; the physical scenario remains unchanged.
The entered safety buffer adds a percentage to that base requirement. It is an explicit planning choice, not a calculated service level and not a promise that stockouts will be prevented.
One signal represents one container in this model. The exact container requirement is always rounded up so the represented quantity is not lower than the buffered requirement. The equation is a transparent product model, not a claim that one formula is the universal Kanban standard.
Formula & worked example
lead-time demand = average demand rate × replenishment lead time safety units = lead-time demand × safety buffer ÷ 100 buffered requirement = lead-time demand + safety units exact containers = buffered requirement ÷ units per container whole signals/containers = exact containers rounded up
120 units per day, 2 days replenishment lead time, 80 units per container and a 10% safety buffer
- Demand during replenishment: 120 × 2
- 240 units
- Safety units: 240 × 10%
- 24 units
- Exact containers: 264 ÷ 80
- 3.3 containers
Round 3.3 up to 4 whole signals/containers. They represent 320 units, leaving 56 units above the buffered requirement because containers are indivisible in this model.
How this calculation works
The calculation follows the formulas, definitions and assumptions explained on this page. The references below support the method and any stated boundaries.
Official sources
- Lean Enterprise Institute — Kanban — Kanban as a production or withdrawal signal, including the simple one-card-per-container case
- Lean Enterprise Institute — Lean material handling — Example linking signals with usage, replenishment frequency and standard container quantity
- University of Cambridge IfM — Kanbans — Card and container context, with operational card-count adjustment