# Heijunka Box

Operations · `Heijunka Box` · verification: source checked

A heijunka box, also called a leveling box, is a tool that holds kanban cards in rows for product types and columns for identical time intervals. At each interval, a material handler withdraws kanban from the box and distributes them to production processes. It levels production volume and mix by using short time increments instead of releasing a shift, day, or week of demand to the floor.

## Specification

| Property | Value |
|---|---|
| Kind | tool |

## Study notes

- Each horizontal row is for one product type (one part number); each vertical column is an identical time interval for paced withdrawal of kanban.
- In the illustrated example, the shift starts at 7:00 a.m. and kanban are withdrawn every 20 minutes.
- Each kanban in a slot represents one pitch of production for one product type.
- Pitch is takt time multiplied by pack-out quantity.
- Product A has a 20-minute pitch with one kanban per interval; Product B has a 10-minute pitch with two kanban per slot; Product C has a 40-minute pitch with kanban in every other slot.
- Products D and E share a production process with a 20-minute pitch and a demand ratio of 2:1 for D versus E; D has kanban in the first two intervals and E in the third, repeating in the same sequence.
- The box levels demand by short time increments and by mix, for example producing Product D and Product E in a steady ratio with small batch sizes.

## Sources

1. [Heijunka Box - Lean Enterprise Institute](https://www.lean.org/lexicon-terms/heijunka-box/) (accessed 2026-10-25)

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