Calculate minimum and maximum inventory levels, reorder triggers and suggested replenishment quantities. Build a Min/Max policy, test it against your current inventory position, or process multiple SKUs at once.
Recommended starting levels. Min is the reorder trigger; Max is the order-up-to target. Choose how the Min–Max gap should be sized.
Operational Min/Max check. Net current inventory, open supply and open demand, then determine whether a replenishment order should be suggested.
Multiple SKUs. Paste demand and policy data from a spreadsheet. WareStat calculates recommended Min, Max and current replenishment quantity for each row.
Results
| Component | Units | Days |
|---|
| Scenario | Min | Max |
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| SKU | Min | Max | Position | Status | Suggested Order |
|---|
A Min/Max inventory system uses two control levels for each SKU: Min is the replenishment trigger, and Max is the level you replenish up to. This calculator can build recommended Min/Max levels from demand and lead time, then test the policy against current stock, incoming supply, and open demand.
Min/Max Inventory Formula
A practical starting point for continuous-review inventory is:
Min = Average Daily Demand × Lead Time + Safety Stock
The Min level effectively acts as the reorder point. Max, on the other hand, can be set in a few different ways depending on how the item is purchased:
- Review-cycle method: Max = Min + demand during the order/review cycle
- Fixed-quantity method: Max = Min + standard replenishment quantity, such as EOQ or a supplier pack quantity
- Coverage method: Max = average daily demand × target days of supply
Min Is a Trigger, Not Just Safety Stock
In a standard Min/Max replenishment policy, Min represents the inventory position at which a new order should be considered. That means it needs to cover expected demand during replenishment lead time, plus any safety stock buffer on top. Safety stock alone isn’t the same thing as the Min trigger.
How Replenishment Quantity Is Calculated
For an operational Min/Max check, WareStat first calculates:
Inventory Position = On Hand + On Order − Open Demand
If inventory position falls below Min, the basic replenishment quantity becomes:
Order Quantity = Max − Inventory Position
From there, the calculator can adjust that figure for a supplier minimum order quantity (MOQ), a fixed case or pallet multiple, and a maximum order quantity.
Why Use Inventory Position Instead of On-Hand Stock?
On-hand quantity by itself can trigger unnecessary purchase orders. If 300 units are already inbound, that supply should normally be accounted for before another order goes out. Open or reserved demand pulls in the opposite direction, since those units are already committed. Netting both quantities together produces a more useful replenishment signal.
How Should Max Be Set?
There’s no single universal Max formula. A common approach is to set the Min–Max gap equal to demand over one normal review or ordering cycle. Businesses that buy in fixed quantities can instead add an EOQ, carton, pallet, or production batch on top of Min. A days-of-supply ceiling tends to work better when storage capacity or shelf life matters more than order-cost optimization.
Min/Max vs. EOQ
EOQ focuses on the economically efficient order quantity, while Min/Max is a replenishment policy that defines both when to order and how far to replenish. The two can be combined by using the reorder point as Min and EOQ as the Min–Max gap.
Min/Max vs. Safety Stock
Safety stock is the uncertainty buffer inside the policy — it protects against demand or lead-time variability, while Min folds in both expected lead-time demand and that buffer. When demand or supplier lead time is volatile, it’s worth calculating safety stock separately rather than picking an arbitrary percentage.
Frequently Asked Questions
Should I reorder when stock equals Min or falls below it?
It depends on the implementation. Some systems trigger at or below Min, while others generate a suggestion only once available inventory drops below Min. Keep the rule consistent with whatever ERP or WMS stores the parameters.
Can on-order inventory be included?
Yes. The Replenishment Check uses inventory position, so existing supply can be added in and committed demand deducted before deciding whether another order is needed.
What happens when MOQ is larger than the required order?
The practical replenishment quantity has to be raised to the MOQ. This can push inventory above the theoretical Max — useful information when negotiating supplier quantities or reviewing storage requirements.
How often should Min and Max levels be reviewed?
Review them whenever demand, lead time, safety stock, supplier constraints, or ordering frequency changes materially. Seasonal and fast-moving products generally need more frequent updates than stable, slow movers.