Reorder Point Calculator
Calculate when to reorder inventory based on lead time and daily usage.
Extra days of inventory to buffer against delays. 0 = no safety stock.
This tool is for informational and educational purposes only. It is not a substitute for professional financial, medical, legal, or engineering advice. See Terms of Service.
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The reorder point tells you exactly when to place a new order so stock arrives before you run out:
- Enter daily usage. How many units you sell or use per day on average. Use your historical average or a conservative estimate if usage is variable.
- Enter lead time. How many days it takes from placing an order to receiving it. Include processing time, shipping time, and any inspection delays.
- Set safety stock days. The number of extra days of inventory you want as a buffer. Common values are 3-7 days for stable suppliers, up to 14+ days for international or unreliable suppliers.
When your inventory falls to the reorder point quantity, place a new order. The stock will arrive just as your safety stock begins to be drawn down.
About Reorder Point Calculation
The formula is: ROP = (Daily Usage x Lead Time Days) + Safety Stock. Safety stock = Daily Usage x Safety Days. For example: 50 units/day usage, 7-day lead time, 3 days safety stock gives ROP = (50 x 7) + (50 x 3) = 350 + 150 = 500 units. Place a new order when inventory drops to 500 units.
Safety stock accounts for supplier delays, demand spikes, and receiving/inspection time. Without safety stock, any delay in delivery will cause a stockout. For ABC inventory management, use higher safety stock days for A-class items (high revenue impact) and less for C-class items.
Frequently Asked Questions
What is the reorder point formula?
The basic reorder point formula is: ROP = (Average Daily Usage x Lead Time in Days) + Safety Stock. Safety stock is typically calculated as Average Daily Usage multiplied by the desired safety buffer in days. The reorder point represents the inventory level at which a new order should be placed to avoid stockout before the next delivery arrives.
How much safety stock should I keep?
The right safety stock level depends on demand variability, supplier reliability, and the cost of stockouts versus holding costs. A common simple rule is to keep safety stock equal to a fixed number of days of supply: 3-5 days for reliable domestic suppliers, 7-14 days for less reliable or international suppliers. More sophisticated methods calculate safety stock based on standard deviation of demand or lead time, which gives more precise results for high-volume items.
What is the difference between reorder point and reorder quantity?
The reorder point is the inventory level that triggers a new purchase order. The reorder quantity (also called order quantity or EOQ) is how much to order when that trigger is reached. This calculator determines when to order. A separate Economic Order Quantity (EOQ) calculation determines how much to order to minimize total ordering and holding costs. Both are needed for a complete inventory replenishment policy.
How do I handle variable lead times in the reorder point?
For variable lead times, use the maximum expected lead time rather than the average, or add the lead time variability to your safety stock days. For example, if lead time averages 7 days but sometimes runs 10 days, either use 10 days as your lead time input or use 7 days lead time with 3 extra safety stock days to cover the maximum delay. For high-value or critical inventory, using maximum lead time is the more conservative and safer approach.