Kanban & Supermarket Sizing

Use the Kanban & Supermarket Sizing form to quantify the number of kanban containers and the maximum inventory.
The Kanban & Supermarket Sizing form answers the following questions.
• How much inventory should be maintained at a process?
• How many kanbans should be used?
• What size should the kanbans be?

How-to

Single Unit is the most common and traditional kanban system.

1. From Kanban Type, choose the type of kanban.
Single Unit
Each container of a fixed size has a kanban. When the container is removed from the supermarket, the kanban is removed and returned to the supplier operation to signal the need to produce an additional kanban quantity. This the most common and traditional kanban system.
Two Bin
Two bins, or containers, are used. Each container of a fixed size contains a quantity equal to the production demand rate multiplied by the replenishment time. When a container is empty, it is returned to the supplier operation to signal the need to replenish it.
Note

Because there are only two containers in this system, the maximum inventory is twice the container quantity.

Multi-bin
This is similar to the two bin system because reordering is based on a certain level of inventory, instead of individual container kanban. However, unlike the two bin system, containers can be of any constant size smaller than the reorder quantity. The reorder point specifies the number of containers to reorder.
2. Enter the following data.
• Demand Rate (units per): Rate at which inventory is consumed.
• Replenishment Time: The time required to restock a bin, or container, once the request is made.
• Safety Stock (%): The percent of inventory that exists to protect against downtime.
3. For Single Unit and Multi-bin, enter the container size.

Calculations

• Calculations for the Single Unit kanbans.
Supermarket Size (units)
Supermarket Size (units) = Demand Rate * Replenishment Time * (1 + Safety Stock)

Units are rounded up to the next integer.

Supermarket Size (containers)
Supermarket Size (containers) = Supermarket Size (units) / Container Size (units)

Containers are rounded up to the next integer.

Number of kanban cards in supermarket
Number of kanban cards in supermarket = Supermarket Size (containers)
• Calculations for the Two Bin kanbans.
Number of units in bin
Number of units in bin = Demand Rate * Replenishment Time * (1 + Safety Stock)

Units are rounded up to the next integer.

Number of bins
Number of bins = 2
Total number of units in supermarket
Total number of units in supermarket = 2 * (Number of units in bin)
• Calculations for the Multi-bin kanbans.
Trigger Point (units)
Trigger Point (units) = Demand Rate * Replenishment Time * (1 + Safety Stock)

Units are rounded up to the next integer.

Trigger Point (containers)
Trigger Point (containers) = Supermarket Size (units) / Container Size (units)

Containers are rounded up to the next integer.

Total number of containers in supermarket
Total number of containers in supermarket = 2 * Trigger Point (containers)