397. FSN

397.1. FSN Analysis (Fast / Slow / Non-moving)

Classify items by movement frequency — how often they’re picked, issued, or sold. Independent of value (ABC) and variability (XYZ).

397.1.1. The frequency split

• F items (Fast-moving): picked frequently — multiple times per week or daily.
• S items (Slow-moving): picked occasionally — a few times per month or quarter.
• N items (Non-moving): no issue activity for an extended period (typically 6+ months); effectively dead stock.

Thresholds depend on context. Common rules:

397.1.2. Why classify by movement

FSN is about operational friction, not financial impact:

• Warehouse layout: F items go into the pick-face / golden zone; N items go into deep storage or get culled.
• Cycle counting frequency: F items counted often; N items counted rarely.
• Obsolescence detection: a creeping shift from S to N is an early warning that an SKU is dying.
• Working capital cleanup: N items tie up cash with zero return — periodic FSN review forces a write-off conversation.

ABC tells you “where is the money sitting?”. FSN tells you “what’s actually moving?”. Both are needed: an A but N item (high value, no movement) is high-priority dead stock — sell it off, don’t ignore it.

397.1.3. Procedure

1. Pull issue / pick / sales records over a window (typically 6–12 months).
2. For each SKU, count the number of issues (or compute days since last issue).
3. Classify by your chosen thresholds.
4. Cross-reference with ABC: high-value non-movers are urgent.

397.1.4. Adjacent metrics

• Inventory turnover = annual demand / average inventory. High = F-class; low = S or N.
• Days of supply = average inventory / daily demand. The inverse view.
• Last-issue date: most direct test for N-class.