Determine when to reorder and how much safety stock to carry. All calculations run locally in your browser.
How much daily demand varies. Set to 0 if demand is constant.
How much lead time varies. Set to 0 if your supplier is consistent.
Reorder Point
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Place a new order when stock reaches this level
Safety Stock
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Lead Time Demand
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Economic Order Quantity (EOQ)
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Optimal order size to minimize total costs
Formula: ROP = (Avg Demand × Lead Time) + Safety Stock
A properly configured reorder point ensures purchase orders are triggered early enough to receive new stock before existing inventory is depleted. The calculation accounts for two sources of uncertainty: fluctuations in customer demand and variability in supplier lead times.
Organizations that rely on manual reorder decisions or static min/max levels frequently experience either stockouts (lost sales, production delays) or excess inventory (increased carrying costs, obsolescence risk). A data-driven reorder point eliminates both problems.
The service level represents the probability of not experiencing a stockout during a replenishment cycle. A 95% service level means you expect to fill orders from stock 95% of the time. Higher service levels require exponentially more safety stock - moving from 95% to 99% roughly doubles the buffer.
Modern warehouse management systems like Inventory Pro help teams review these calculations across thousands of SKUs, using demand patterns and lead times to guide replenishment decisions.
The reorder point is the inventory level at which a new purchase order should be placed to replenish stock before it runs out. It accounts for lead time demand and safety stock.
Safety stock is the buffer inventory held to protect against variability in demand and lead time. This calculator uses the standard formula: Z-score × √(lead time × demand variance² + average demand² × lead time variance²).
A 95% service level is standard for most inventory operations. Critical items (medical, safety) may warrant 99%. Low-priority items may use 90% to reduce carrying costs.
EOQ is the order size that minimizes total ordering and holding costs. It balances the cost of placing orders against the cost of carrying inventory.
Inventory Pro suggests reorder points and helps generate purchase orders based on stock levels, usage history, and supplier lead times. We have been developing inventory solutions since 1996.
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