Supply ChainFlow

Inventory

Raw materials, work-in-process, and finished goods held in the system — one of the eight wastes when excessive.

Inventory exists in three forms: raw materials, work-in-process, and finished goods. Some is necessary to decouple steps and buffer variability, but excess inventory is one of the 8 wastes — it ties up cash, hides problems, and risks obsolescence.

Lean treats inventory as a symptom to be reduced as underlying variability is removed, while supply-chain math (EOQ, reorder points, safety stock) sets the necessary minimums.

Go Deeper
Inventory Management guide→Safety Stock Calculator→
Related Terms
WIP
Inventory that has entered production but is not yet finished — the lever that controls lead time via Little's Law.
Safety Stock
Extra inventory held as a buffer against demand and supply variability to protect service level.
Economic Order Quantity
The order quantity that minimizes the combined cost of ordering and holding inventory.
Reorder Point
The inventory level at which a replenishment order should be placed to avoid a stockout during the lead time.
8 Wastes
The eight categories of waste lean targets: Defects, Overproduction, Waiting, Non-utilized talent, Transportation, Inventory, Motion, Extra processing.
ABC Analysis
An inventory categorization that ranks items into A, B, and C classes by value so control effort is focused where it matters.

Put Inventory into practice

SymplProcess turns these concepts into working models, calculators, and templates your whole team can use — no spreadsheets required.

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