SAP Reorder Point and Safety Stock Calculator
Reorder point planning in SAP (MRP types VB and VM) triggers a requirement when available stock drops to the reorder point. This calculator derives the reorder point and safety stock you would maintain in the material master from your own demand statistics and lead time.
Your numbers
Average consumption per working day.
Measure from consumption history, for example MSEG goods issues.
Field Planned Delivery Time in MRP 2, or the info record value.
Field GR processing time in MRP 2: inspection and putaway after receipt.
Your results
Assumes normally distributed daily demand and a fixed lead time. If supplier lead time is also variable, add that variance or use a historical simulation.
Reorder point and safety stock vs planned delivery time
Sweeps Planned delivery time from 1 to 60, holding your other inputs fixed.
Safety stock review from your SAP data
Optional: send us an export of consumption history and current MARC values and we will highlight materials where settings look off.
Optional. The tool and every export work without this. No spam.
How to use the calculator
Enter average daily demand and its standard deviation, taken from goods issue history. Enter the planned delivery time and GR processing time exactly as they appear on the MRP 2 view, because SAP adds both to schedule the order. Pick a service level, which is the probability of not stocking out during a replenishment cycle. The result gives the safety stock for field Safety stock and the reorder point for field Reorder point on the MRP 1 view.
- Use working days if your plant calendar skips weekends
- Update the numbers after a supplier change
- Run per plant, since MARC is plant specific
The method
Lead time is planned delivery time plus GR processing time. Demand during lead time is average daily demand times lead time. Safety stock is the Z score for the service level times the daily standard deviation times the square root of lead time. The reorder point is demand during lead time plus safety stock. Standard deviation scales with the square root of time because independent daily variations partly cancel out, which is why doubling lead time raises safety stock by about 41 percent, not 100 percent.
Reading the result in SAP
Maintain safety stock in the MRP 1 view and the reorder point in the same view for MRP type VB. For MRP type VM with automatic reorder point planning, SAP can compute the reorder point from forecast values if the forecast parameters are maintained. The safety stock value output shows the working capital you are tying up for service, which helps justify lower service targets on low-criticality C parts. Compare the output against your current values and list the largest gaps first.
Common mistakes
Frequent errors are mixing calendar days with working days, using monthly standard deviation with a daily average, and forgetting that open purchase orders count toward available stock for the trigger. Also, stale planned delivery times in the info record are a leading cause of stockouts: MRP uses the number even if suppliers have slipped for months.
- Keep units consistent: all daily or all weekly
- Refresh planned delivery times quarterly
- Do not set 99.9 percent service for every part
Frequently Asked Questions
Which SAP fields hold the reorder point and safety stock?
Both live in the MRP 1 view of the material master at plant level: Reorder Point (MARC-MINBE) and Safety Stock (MARC-EISBE). The reorder point is used by MRP types VB and VM.
What is GR processing time?
It is the number of working days needed after goods receipt for inspection, putaway and booking before stock is available. SAP adds it to the planned delivery time when scheduling procurement.
Should safety stock include supplier lead time variability?
Ideally yes. This tool only models demand variability. If lead times vary a lot, add the lead time standard deviation using the combined formula, or raise service level modestly and review actual receipt dates.
How does SAP use the reorder point?
During the MRP run for reorder point planning, if plant stock plus open receipts falls below the reorder point, MRP creates a purchase requisition or planned order based on the lot size procedure.
Netray can recompute these values for every material from your live SAP history and show where current settings differ, read-only, with human approval before anything is changed.
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