A reorder point answers one operational question: at what on-hand quantity should a retailer start replenishment? It is more useful than ordering on a fixed weekday because it connects the decision to actual sales and the time needed to receive new stock. The calculation is simple; choosing honest inputs is the important part.
The basic reorder-point formula
Reorder point = average daily unit sales × replenishment lead time in days + safety stock.
Suppose a product sells an average of 3 retail units per day, a normal replenishment takes 8 days and the store keeps 10 units as safety stock. The reorder point is 3 × 8 + 10 = 34 units. When available stock reaches 34, the buyer starts the next order. This number is a trigger, not the order quantity.
Use sellable units throughout the calculation
Sales usually appear in retail units while wholesale orders may use displays or cases. Convert everything to one unit before calculating. If a case contains 60 retail units, 34 units is slightly more than half a case. The pack-conversion guide explains how to document that relationship without mixing cases and pieces.
Choose a sales window that reflects the product
A 30-day average can work for a steady item, but a new product or seasonal item needs more context. Compare at least two windows when possible. A recent 14-day increase may show a real change, a promotion or a one-time event. A 90-day average may smooth that event but react slowly. Record the window beside the number so another buyer can reproduce the result.
- Exclude days when the product was out of stock if those zero sales do not represent demand.
- Separate returns or inventory corrections from customer sales.
- Calculate per SKU or exact variant rather than for a broad product family.
- Review new items more often until their sales pattern becomes meaningful.
Build safety stock from uncertainty
Safety stock protects against variation in demand or lead time. It should have a reason. Ask how much sales can rise during the lead time, how often deliveries arrive later than planned and what an empty shelf would cost. A slow, replaceable item may need little buffer. A core item with variable delivery timing may need more.
One practical method is to cover several additional days of typical sales. At 3 units per day, a four-day buffer is 12 units. More advanced methods can use maximum demand and maximum lead time, but extra precision is useful only when the underlying records are reliable.
Distinguish on-hand, available and on-order stock
Physical on-hand quantity may include damaged, reserved or quarantined units. Use available stock for the trigger. Then check open purchase orders to avoid ordering the same requirement twice. A simple buying worksheet can show:
| Measure | Example |
|---|---|
| Physical on hand | 38 units |
| Reserved or not sellable | 6 units |
| Available | 32 units |
| Open purchase order | 0 units |
| Reorder point | 34 units |
In this example, the available quantity has crossed the trigger even though the physical count looks higher.
Review the number instead of treating it as permanent
Update the calculation when sales pace, case pack, supplier timing or seasonality changes. Monthly review may suit core items; a slower item might be reviewed quarterly. Record the old value, new value, date and reason. That history reveals whether repeated stockouts come from the forecast, lead time or execution.
Test the trigger against two realistic scenarios
Before adopting the number, ask what happens if delivery is three days late and what happens if sales temporarily rise by one unit per day. The exercise does not need to predict every event. It shows whether the chosen safety stock can absorb a plausible variation or whether the buyer is accepting a likely gap. Record the scenario beside the decision so the buffer has a visible reason.
Also check the minimum order and case pack. A mathematically correct trigger can still produce excess inventory when the smallest order adds many weeks of supply. In that situation, adjust the assortment role or ordering plan rather than hiding the extra coverage inside the formula.
Pair the reorder point with weeks-of-supply analysis to compare products with different sales speeds. Use the inventory-aging review when stock remains far above its target. Before ordering, confirm the exact SKU and pack in the wholesale catalog; current price and availability belong in the authenticated ordering flow.
Content notes
A plain-language reorder-point method for independent retailers, with a worked example, safety-stock questions and a review cadence that adapts to real sales and lead times.
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Reviewed by: MWHQ GOODS Editorial Team