Glossary term
Economic Order Quantity (EOQ)
Economic order quantity is an inventory formula that estimates the order size that minimizes ordering and holding costs.
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What Is Economic Order Quantity (EOQ)?
Economic order quantity, or EOQ, is an inventory model that estimates the order size that minimizes the combined cost of ordering inventory and holding it. It is used in operations, accounting, procurement, and supply-chain planning.
The basic EOQ model assumes demand, ordering cost, and holding cost are known and stable. That makes it a useful starting point, but not a complete inventory system for every business.
Key Takeaways
- EOQ estimates the order quantity that minimizes ordering and holding costs.
- Ordering too often raises administrative or setup costs.
- Ordering too much raises storage, insurance, spoilage, and capital costs.
- The classic formula assumes stable demand and costs.
- Real businesses often adjust EOQ for lead times, discounts, stockouts, and uncertainty.
EOQ Formula
D is annual demand in units. S is the ordering or setup cost per order. H is the annual holding cost per unit. The formula balances the tradeoff between ordering frequently and carrying too much inventory.
EOQ is often paired with reorder-point planning. EOQ answers how many units to order, while the reorder point answers when to place the order so inventory arrives before stock runs out.
What EOQ Balances
Cost type | What increases it | EOQ tradeoff |
|---|---|---|
Ordering cost | More frequent orders | Lower with larger orders |
Holding cost | More inventory on hand | Lower with smaller orders |
Stockout risk | Too little inventory | Handled with safety stock, not basic EOQ |
Purchase discounts | Quantity price breaks | May justify ordering above EOQ |
EOQ can also support cash-flow planning because inventory ties up working capital. Ordering less often may reduce ordering work, but it can also leave more money sitting in stock that has not yet been sold.
The model is most helpful for repeatable items with predictable demand. It is less useful for one-off purchases, highly seasonal products, or goods with short shelf lives.
Limits and Misunderstandings
EOQ is not the same as a reorder point. EOQ estimates how much to order; a reorder point estimates when to order based on lead time and demand.
The classic formula can be too simple when demand is seasonal, suppliers are unreliable, storage is constrained, products expire, or quantity discounts are material. It should guide judgment, not replace it.
The Bottom Line
Economic order quantity helps businesses find a cost-efficient inventory order size. It is useful because it makes the ordering-versus-holding tradeoff explicit, but real inventory decisions need lead time, risk, and operating context.