Reorder Point Calculator
Find the exact inventory level at which you should place a new order. Use this when setting up automated purchasing triggers or reviewing stock replenishment policies.
About this calculator
The reorder point (ROP) is the inventory level that signals it's time to place a new purchase order. It ensures stock arrives before you run out, accounting for both normal consumption during lead time and a buffer for unexpected demand spikes. The formula is: ROP = (Lead Time × Daily Demand) + Safety Stock. Lead time is the number of days between placing and receiving an order. Daily demand is the average number of units sold per day. Safety stock is the extra buffer held to absorb demand variability. Together, the lead time demand component covers expected consumption, while safety stock covers uncertainty. Getting the reorder point right reduces both stockouts and excess carrying costs.
How to use
Suppose a warehouse sells 50 units per day, has a supplier lead time of 7 days, and holds 100 units as safety stock. Step 1 — Calculate lead time demand: 7 days × 50 units/day = 350 units. Step 2 — Add safety stock: 350 + 100 = 450 units. So the reorder point is 450 units. When inventory drops to 450 units, place a new order. By the time the order arrives 7 days later, approximately 350 units will have been consumed, leaving roughly 100 units of safety stock intact.
Frequently asked questions
What is the difference between reorder point and safety stock?
The reorder point is the inventory level that triggers a new purchase order, while safety stock is just one component within it. Safety stock is the extra buffer added on top of the lead time demand to protect against variability in demand or supplier delays. You can think of safety stock as insurance, whereas the reorder point is the full signal that combines expected usage during lead time with that insurance buffer. Without safety stock, your reorder point only covers average consumption and leaves you vulnerable to stockouts if demand spikes or the supplier is late.
How does lead time affect the reorder point calculation?
Lead time directly multiplies daily demand in the formula, so longer lead times produce significantly higher reorder points. If your supplier takes 14 days instead of 7, your reorder point roughly doubles (assuming the same daily demand and safety stock). This means you must hold more inventory on-hand at all times to avoid running out while waiting for the order to arrive. Businesses with unreliable or long-lead-time suppliers should pay close attention to this figure and consider negotiating shorter lead times to reduce carrying costs.
When should I recalculate my reorder point?
You should recalculate your reorder point whenever any of the underlying variables change meaningfully — for example, if your average daily demand increases due to a seasonal spike, if your supplier's lead time changes, or if you revise your safety stock policy. Many inventory managers review reorder points quarterly or after any significant supply chain disruption. Outdated reorder points are a common cause of both stockouts and excess inventory, so keeping them current is a key part of lean inventory management.