Economic Order Quantity Calculator

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Order the Right Amount Every Time with the Economic Order Quantity Calculator

Every time you place a purchase order, you pay ordering costs: processing fees, shipping charges, receiving labor, and quality inspection time. But every unit sitting in your warehouse also costs money: storage space, insurance, depreciation, and tied-up capital. The Economic Order Quantity Calculator finds the order size that minimizes the total of both costs, striking the perfect balance between ordering too frequently and ordering too much.

EOQ is one of the oldest and most trusted formulas in inventory management, and for good reason. It mathematically determines the order quantity where your annual ordering costs exactly equal your annual holding costs. At that intersection, your total inventory cost hits its lowest possible point.

How to Use the EOQ Calculator

You need three inputs. First, your annual demand: how many units of this product you expect to sell or consume in a year. Second, your ordering cost per order: the fixed cost you incur every time you place a purchase order, including administrative time, shipping, and receiving. Third, your annual holding cost per unit: what it costs to store one unit for an entire year, including rent allocation, insurance, and the opportunity cost of the capital invested.

Enter those three figures, and the Economic Order Quantity Calculator returns your optimal order size, the number of orders you'll place per year, the time between orders, and a cost breakdown showing your total annual ordering costs, holding costs, and combined inventory costs.

Who Should Care About EOQ?

Procurement managers use EOQ to standardize their purchasing decisions across hundreds of SKUs. Instead of gut-feel ordering where the purchasing team rounds up to the nearest pallet because it seems right, EOQ provides a data-driven quantity that actually minimizes cost.

Small business owners who order products from wholesalers can save significant money by right-sizing their orders. Ordering 500 units instead of 1,000 might mean ordering twice as often, but if the holding cost savings outweigh the extra ordering cost, the smaller batch wins. EOQ tells you exactly where that crossover happens.

Manufacturing planners use EOQ to determine production batch sizes for internally manufactured components. The same trade-off applies: setup costs for production runs mirror ordering costs, and work-in-progress inventory mirrors holding costs.

A Real-World Calculation

Your business sells 10,000 units annually of a particular product. Each purchase order costs you $50 to process and receive. Holding one unit in your warehouse for a year costs $2 in storage, insurance, and capital opportunity cost.

The EOQ formula yields approximately 707 units per order. That means you'll place about 14 orders per year, roughly one every 26 days. Your annual ordering cost will be around $707, your holding cost around $707, and your total inventory cost approximately $1,414. Any other order quantity, whether larger or smaller, results in a higher total cost.

Limitations and When to Adjust

EOQ assumes constant demand, which rarely happens in practice. If your product has strong seasonal swings, calculate EOQ for each season separately or use the annual figure as a baseline and adjust orders up or down around seasonal peaks.

Quantity discounts can override the EOQ recommendation. If your supplier offers a 10% discount for orders above 1,000 units and your EOQ says 707, run the numbers both ways. Sometimes the discount savings exceed the extra holding costs, making the larger order more economical despite what the pure EOQ suggests.

Shelf life constraints also matter. If your product expires in 90 days, ordering a year's supply is obviously wrong regardless of what EOQ says. Always apply common sense alongside the mathematical optimum.

Instant, Private, and Free

The Economic Order Quantity Calculator runs entirely in your browser. Your cost data, demand figures, and supplier pricing stay on your device. No account required, no data transmitted, just solid inventory math at your fingertips whenever you need it.