Inventory Management Intermediate

Replenishment

Also known as: Stock Replenishment, Inventory Replenishment, Restocking

Definition

Replenishment is the process of restocking inventory to ensure products are available when needed. This includes both internal warehouse replenishment (moving stock to pick locations) and external replenishment (ordering from suppliers).

Types of Replenishment

Internal (Warehouse)

Moving inventory from bulk/reserve storage to forward pick locations:

  • Reserve-to-pick transfers
  • Pallet-to-case breakdowns
  • Case-to-each replenishment

External (Supply Chain)

Ordering new inventory from suppliers:

  • Scheduled purchase orders
  • Automatic reorder triggers
  • Demand-based ordering

Replenishment Strategies

Strategy How It Works Best For
Min/Max Order when stock hits minimum, order up to maximum Simple, stable demand
Reorder Point Order fixed quantity when level triggers Consistent lead times
Periodic Review Check and order at set intervals Many SKUs, low volume
Demand-driven Order based on forecasted sales Variable demand

Replenishment Formulas

Reorder Point

ROP = (Average Daily Usage × Lead Time) + Safety Stock

Example:

  • Daily usage: 50 units
  • Lead time: 5 days
  • Safety stock: 100 units
  • ROP = (50 × 5) + 100 = 350 units

Economic Order Quantity (EOQ)

Balances ordering costs against holding costs to find optimal order size.

Key Metrics

  • Fill rate - % of demand met from available stock
  • Stockout frequency - How often you run out
  • Inventory turns - How fast stock sells through
  • Days of supply - How long current stock will last

Replenishment Challenges

  • Inaccurate demand forecasts
  • Supplier lead time variability
  • Storage capacity constraints
  • Seasonal demand spikes
  • SKU proliferation

Automation

Modern WMS systems automate replenishment:

  • Trigger picks when forward stock is low
  • Generate purchase orders automatically
  • Prioritize based on velocity and urgency
  • Optimize replenishment timing and quantities
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