| Scenario | Daily Sales | Reorder Point | Safety Stock | Days Remaining |
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This calculator uses three core inventory management formulas. The reorder point tells you exactly when to place a new order: it equals your average daily sales multiplied by lead time, plus a safety stock buffer. Safety stock is the cushion of extra units you keep to protect against unexpected demand spikes or supplier delays. The Economic Order Quantity (EOQ) calculates the optimal number of units to order each time, balancing the cost of placing orders against the cost of storing inventory.
Together, these metrics give you a complete picture of when to order, how much to order, and how much it costs โ helping you avoid both stockouts and excess inventory.
Running out of stock is one of the most costly mistakes an online seller can make. On platforms like Amazon, stockouts can cause your listing to lose ranking, reducing sales even after you restock. On Etsy and Shopify, out-of-stock products frustrate customers and push them to competitors. Setting a proper reorder point โ and sticking to it โ ensures continuous availability while keeping storage costs manageable.
This free calculator helps sellers of all sizes, from handmade artisans to wholesale resellers, determine the right time to reorder and the right quantity to order. No spreadsheets needed.
EOQ was developed by Ford W. Harris in 1913 and remains one of the most widely used inventory management formulas. The key insight is that ordering too frequently wastes money on shipping and processing, while ordering too much wastes money on storage and tied-up capital. EOQ finds the sweet spot that minimizes total cost. The formula is: EOQ = √(2 × Annual Demand × Order Cost ÷ Holding Cost).