Retail replenishment is one loop: know when each SKU needs reordering, decide how much against pack sizes and minimums, send each supplier their order, receive what actually arrives at what it actually cost, and let the result sharpen the next reorder. Run it well and cash sits in the right inventory; run it from memory and you stock out of winners while dead stock eats the storeroom.
This is the hub for the whole loop for retailers — Shopify and brick-and-mortar POS alike. Each section gives the working version, then links the deep guide, tool, and concept pages. It's the retail sibling of Restaurant Purchasing, Complete.
Step 1: Know when to reorder — computed, not vibes
The core object is the reorder point: expected demand during the supplier's lead time, plus safety stock sized to demand and lead-time variability. POS products vary: some offer thresholds, planning recommendations or connected inventory apps. Recheck whichever policy you use when demand or lead time changes — which is why best-sellers still stock out.
- Compute it: Reorder Point Calculator · Par Level Calculator
- Classify first: Demand Pattern Classifier — smooth, intermittent, erratic, and lumpy SKUs need different math