Infor LN Safety Stock and Reorder Point Calculator
Infor LN lets you protect an item with safety stock or with safety time, and planners often set them by feel. This calculator derives both from service level and measured variability. Results export to PDF or Excel.
Your numbers
Your results
Assumes normally distributed demand and lead time that are independent of each other. Intermittent demand needs a different method.
Safety stock and reorder point vs lead time
Sweeps Average replenishment lead time from 1 to 90, holding your other inputs fixed.
Safety stock review on your LN data
An optional expert pass over buffer settings against actual variability.
Optional. The tool and every export work without this. No spam.
How to use it
Pull average daily demand and its standard deviation from issue history, and the average and standard deviation of supplier lead time from receipts. Choose the service level the business actually wants for the item class. The result is the safety stock, the reorder point and the same buffer expressed in days. Use safety stock when demand is the main uncertainty and safety time when supply timing is the main uncertainty.
The formula
Safety stock is Z times the square root of lead time times demand variance plus average demand squared times lead time variance. Z comes from the normal distribution for the chosen service level, for example 1.645 at 95 percent. The reorder point is average demand during lead time plus safety stock. Note that service level here is the chance of no stockout per cycle, not the fill rate.
- Higher service costs more than linearly
- Reducing lead time variability often beats adding stock
- Use weekly buckets if daily demand is very lumpy
Common mistakes
Teams copy a single percentage cover to every item. A stable item with a reliable supplier needs far less buffer than a volatile one, and the sweep chart shows how quickly buffer grows with lead time. Also avoid measuring demand variability on forecast error when you buy against firm orders, and remember to refresh the figures when a supplier changes.
Frequently Asked Questions
Safety stock or safety time in LN?
Safety stock suits items with steady lead times and variable demand. Safety time suits items where the risk is late supply, because it moves the planned date earlier regardless of quantity. Many planners use one policy per item group.
Where do I get the standard deviations?
Export daily or weekly issue quantities for 6 to 12 months and compute the standard deviation in Excel. For lead time, compare purchase order date to actual receipt date by supplier and item.
What service level should I choose?
Choose by item importance. Many companies use 98 or 99 percent for critical parts, 95 percent for general stock and 90 percent for low value C items. Each step up costs noticeably more inventory.
Does this work for manufactured items?
Yes, treat the production lead time and its variability as the replenishment lead time. Check for component availability separately, since a shortage inflates lead time variability.
If you want this calculated for every LN item from your own history, with the query visible, we can build it read-only against your database.
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