Enter demand, lead-time, and service-level inputs
Add average daily demand, demand standard deviation, average lead time, lead-time standard deviation, and pick a service-level target (z-score).
SAFETY STOCK ESTIMATE
SafetyStock AI
Enter average daily demand, demand variability, average lead time, lead-time variability, and a service-level target to get the genuine combined-variability safety-stock level and reorder point.
- Uses your inputs in a transparent calculation
- Instant result with practical next steps
- No signup required
Planning guidance only. Validate important decisions with customer evidence and your delivery team.
YOUR INPUTS
Build your result
Complete every field. The result updates only when you choose Calculate.
How it works
We apply the standard combined-variability formula
Safety stock is calculated as z × √((avg lead time × demand std dev²) + (avg demand² × lead-time std dev²)) — the genuine textbook formula that accounts for both demand and lead-time variability.
Get safety stock, reorder point, and a buffer ratio
The result shows the safety-stock quantity, the resulting reorder point, and a buffer-to-demand ratio indicating how protected you are relative to lead-time demand.
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Frequently asked questions
Is this a simplified approximation of safety stock?
No. SafetyStock AI implements the standard combined demand-and-lead-time-variability safety-stock formula used in inventory management: z × √((avg lead time × demand std dev²) + (avg demand² × lead-time std dev²)). It does not drop the lead-time-variability term the way a simplified z × demand std dev × √(lead time) approximation would.
Does SafetyStock AI connect to my ERP or inventory system?
No. It computes results only from the figures you enter — it does not connect to any live inventory, ERP, or forecasting system.
Where do I get demand and lead-time standard deviation?
Calculate the standard deviation of your daily sales history for demand variability, and of your supplier's actual delivery times for lead-time variability. Most spreadsheet tools have a built-in STDEV function.
What does the service-level target (z-score) mean?
It represents the probability of not stocking out during the lead time. A 95% service level (z=1.65) means a 5% chance of a stockout before the next replenishment arrives, all else equal.
What is the reorder point, and how is it different from safety stock?
Reorder point is the inventory level at which you should place a new order: average lead-time demand plus the safety-stock buffer. Safety stock alone is just the buffer portion.
Can I use this if my supplier lead time never varies?
Yes — enter 0 for lead-time standard deviation and the formula reduces to the demand-variability-only term, still using the same combined formula structure.
How We Compare
| Feature | MVPHub | Fishbowl | NetSuite |
|---|---|---|---|
| Instant safety-stock and reorder-point calculation | Included | Limited | Limited |
| Live demand forecasting and automated replenishment | Not included | Included | Included |
| No signup required to try the calculation | Included | Not included | Not included |
| Full multi-warehouse inventory management suite | Not included | Included | Included |
Fishbowl and NetSuite provide live demand forecasting and automated replenishment across full inventory systems. MVPHub gives a fast, transparent safety-stock calculation using the genuine combined-variability formula, from figures you enter, with no setup.
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