Plain definitions for the inventory planning terms that get used loosely. Each entry explains the term, the formula where there is one, and when it actually matters.
MOQ is the smallest quantity a supplier will produce or sell in one order. It is their constraint, not yours — so the real skill is deciding when to accept a buy larger than your forecast justifies, and pricing that decision in carrying cost rather than unit cost.
A backorder is an order you have already accepted for stock you do not have. The useful question is not what it means but whether to keep taking it — which turns on your real lead time, what the customer does while waiting, and the channel you sold through.
Inventory turnover measures how many times you sell and replace your inventory during a period—a key indicator of how efficiently your inventory investment generates sales.
A purchase order (PO) is a formal document from buyer to supplier that specifies products, quantities, prices, and delivery terms—your official request to buy goods.
Fill rate is the percentage of customer demand that you fulfill from stock on hand—a direct measure of how often you have what customers want when they want it.
Sales and Operations Planning (S&OP) is a business process that aligns sales forecasts with supply capabilities and financial goals into a single, agreed-upon plan.
Lead time is the total duration between placing an order and having that inventory available to sell—not just shipping time, but every step from order to shelf.
Demand forecasting is the estimate of how many units you will sell, by SKU and by channel, over a stated period. The four methods CPG brands actually use, what data each one needs, the conditions that break them, and how to tell whether yours is working.
A reorder point (ROP) is the inventory level at which you need to place a new order with your supplier—the trigger that tells you it's time to reorder.
Safety stock is the inventory you hold above the forecast to cover the weeks the forecast is wrong. How to size it from your own demand and lead-time variability, with a stated service level and a worked example.