Inventory & Operations
Reorder Point Calculator
Find the stock level that triggers a new order, then compare it with what you have, what is already on order and what is owed.
Your result
Reorder point
Enter daily demand, supplier lead time and a safety-stock buffer. Add current stock to check the trigger.
Calculated on your device. Your numbers aren’t sent or saved.
The method
Cover lead-time demand, then add your buffer
Multiply average daily demand by replenishment lead time to estimate demand before the next delivery. Add whole-unit safety stock and round the total upward to a whole unit. If you also enter stock on hand, the tool compares the threshold with inventory position: on hand plus on order minus backorders. The trigger tells you when to order, not the quantity to purchase.
Example 1
A shipment is already coming, but it is time to reorder
A shop uses 12.5 units per day and waits 7 days for replenishment. Expected lead-time demand is 87.5 units. Add 20 safety units and round 107.5 upward: the reorder point is 108. With 70 on hand, 30 already on order and 5 backordered, inventory position is 95. It is 13 units below the trigger. The 13-unit gap is not an order quantity; check lot size, next receipt and forecast before ordering.
- Lead-time demand
- 87.50 units
- Reorder point
- 108 units
- Inventory position
- 95 units
- Gap to trigger
- 13 units
Example 2
Why on-hand alone can mislead
With 70 on hand and no open orders or backorders, position is 70, well below the 108-unit trigger. If 50 units are already on a confirmed order, position rises to 120. Review when that shipment arrives: the formula treats every on-order unit as usable within its expected schedule.
- On-hand only
- 70 units
- With 50 on order
- 120 units
- Reorder point
- 108 units
Before you calculate
Assumptions & limits
- Use one item at one stocking location. Daily demand and lead time should represent the same operating conditions. Units must match; daily demand is allowed to have fractional averages, while actual stock counts are whole units.
- Safety stock is an input, not calculated here. Estimate it from variability and a service target with the related Safety Stock Calculator or from a documented business policy. Enter 0 only if no buffer is intended.
- Inventory position includes all on-order units as available future supply and subtracts backorders. If some purchase orders are late, uncertain or allocated elsewhere, review them separately; the simple trigger may overstate usable supply.
- Daily demand accepts 0–1,000,000 units with up to two decimals; lead time 0.01–366 days; whole stock counts 0–1,000,000,000. On-hand is required before on-order or backorder counts can be entered. Blank optional counts equal zero only after on-hand is supplied.
- The threshold rounds upward so the planned whole-unit point covers fractional expected demand. It is not an economic order quantity, minimum order quantity, purchase recommendation or stockout guarantee. Seasonality and changing lead time require updated inputs.
Keep in mind
Common mix-ups
Comparing only on-hand stock
A reorder trigger normally compares inventory position, including valid open orders and backorders, with the threshold. Ignoring those commitments can prompt the wrong action.
Confusing the trigger with order quantity
A 108-unit reorder point tells you when to review a purchase order. It does not mean buy 108 units; lot size, minimum order quantity and target coverage are separate decisions.
Using an arbitrary safety buffer
A flat percentage of demand may miss supplier delays or volatile demand. Use observed variability and a deliberate service target when possible.
Sources & calculation notes
Defines reorder point as safety stock plus forecast demand during replenishment lead time, with available stock considering on-hand and planned receipts.
Shows lead-time demand plus safety stock, whole-unit rounding and the model assumptions used in inventory planning.
Calculation and input rules checked: . Engineering validation; no professional accounting review is claimed.