# Kanban and Supermarket Sizing

Use the Kanban and Supermarket Sizing form to quantify the number of kanban containers and the maximum inventory.

• How much inventory should be maintained at a process?
• How many kanbans should be used?
• What size should the kanbans be?

## Guidelines

Single Unit is the most common and traditional kanban system.

## How-to

1. From Kanban Type choose one of the following: values:
Kanban Type Description
Single Unit Each container (of a fixed size) has a kanban (for example, a card). 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 is the most common 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 (optionally modified by a safety factor). 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

The calculations used in the kanban and supermarket sizing tool are displayed in the table:

Kanban Type Calculation Formula
Single Unit Supermarket Size (units) Demand Rate * Replenishment Time * (1 + Safety Stock) (Rounded up to the next integer)
Supermarket Size (containers) Supermarket Size (units) / Container Size (units) (Rounded up to the next integer)
Number of kanban cards in supermarket Equal to Supermarket Size (containers)
Two Bin Number of units in bin Demand Rate * Replenishment Time * (1 + Safety Stock) (Rounded up to the next integer)
Number of bins 2
Total number of units in supermarket 2 * (Number of units in bin)
Multi-bin Trigger Point (units) Demand Rate * Replenishment Time * (1 + Safety Stock) (Rounded up to the next integer)
Trigger Point (containers) Supermarket Size (units) / Container Size (units) (Rounded up to the next integer)
Total number of containers in supermarket 2 * Trigger Point (containers)