Min Max Inventory Calculator
Set the reorder point and maximum stock target, check inventory position, and size replenishment with minimum quantities and pack multiples. Browser-only.
Min/max policy and replenishment
Use consistent demand and lead-time days. EOQ uses 365 days for annual demand and an annual holding cost. Calculations stay in your browser.
Min/max result
| Safety stockEntered safety stock | 60 | Entered safety stock |
|---|---|---|
| Min / reorder point40 × 5 + 60 = 260 | 260 | 40 × 5 + 60 = 260 |
| Policy order quantityEntered quantity | 200 | Entered quantity |
| Max target260 + 200 = 460 | 460 | 260 + 200 = 460 |
| Inventory position180 + 50 − 10 = 220 | 220 | 180 + 50 − 10 = 220 |
| At or below min?220 ≤ 260 | Yes | 220 ≤ 260 |
| Suggested orderShortage 240, MOQ 100, then round up to multiple 50 | 250 | Shortage 240, MOQ 100, then round up to multiple 50 |
| Position after proposed order220 + 250 = 470 | 470 | 220 + 250 = 470 |
MOQ or pack rounding takes the resulting position above max.
Formulas and worked example
Min = average daily demand × lead time + safety stock. Statistical safety stock = z × σdaily × √lead time. Max = min + policy order quantity. That quantity is entered, EOQ = √(2 × (daily demand × 365) × cost per order ÷ annual holding cost per unit), or daily demand × review days.
Inventory position = on hand + on order − backorders. When position ≤ min and the shortage to max is positive, order max − position, raised to MOQ and then rounded up to a whole order multiple. Above min, order zero. Quantities are not rounded before the final pack calculation.
For 40 units/day, lead time 5 days and safety stock 60, min = 40 × 5 + 60 = 260. With a policy quantity of 200, max = 460. On hand 180 + on order 50 − backorders 10 gives position 220, below min. Shortage is 240. With MOQ 100 and multiple 50, the suggested order is 250, leaving position 470. The extra 10 above max comes from pack rounding. These values are locked by a test.
FAQ
When does the min/max policy order?
When inventory position (on hand + on order − backorders) is at or below min. The shortage to max is then raised to MOQ and rounded up to the order multiple. Above min, no order is proposed even if stock is below max. If max is already reached, a zero shortage does not create an MOQ-only order.
What does the statistical safety-stock option assume?
Safety stock = z × daily demand standard deviation × square root of lead time. The selected service level is a cycle service level, not a fill rate. It assumes independent daily demand and a fixed replenishment lead time; it does not include lead-time variability or forecast bias.
How are EOQ and review-period quantities calculated?
EOQ = square root of (2 × annual demand × cost per order ÷ annual holding cost per unit), using annual demand = average daily demand × 365. Both cost inputs must be positive. Zero demand gives zero EOQ. Review quantity = daily demand × review days. Review days set the order size here; this remains a min-triggered policy rather than a scheduled periodic-review policy.
Can a suggested order exceed max?
Yes. MOQ and order multiples can raise the final order above the shortage to max. The result shows inventory position after the proposed order so the overage is visible. The policy quantity sets max before these constraints are applied.
What does zero demand do?
EOQ or demand × review period is zero when average daily demand is zero. Entered safety stock, an entered policy quantity or backorders can still create a positive shortage. Zero shortage at max does not order. Check the policy manually for inactive or new items.
Is my data uploaded?
No. Calculations and CSV parsing run in your browser, and the numbers and files you enter are never sent to a server, unless you choose to share a link, which carries the single-item inputs in its address. The page has no ads, sign-up or third-party trackers; the site host keeps standard anonymous visit counts.
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