ROP (Reorder Point)
ROP (Reorder Point) is the inventory level at which you place the next purchase order: expected demand during the lead time, plus safety stock. It is the single most consequential number in inventory management, because ordering late costs a stockout and ordering early costs cash.
What is ROP?
ROP (Reorder Point) is the inventory level at which you place the next purchase order: expected demand during the lead time, plus safety stock. It is the single most consequential number in inventory management, because ordering late costs a stockout and ordering early costs cash.
It is not a judgement call but a calculation, and it only works when both of its inputs are honest. Lead time measured from your own shipments rather than quoted by a forwarder, and safety stock sized to how variable your demand and supply genuinely are — not picked as a round number that looks sensible.
What happens either side of the line
Order below the correct point and the listing runs dry before replenishment lands. A stockout is expensive in a way that compounds: sales lost during the outage, ranking lost because velocity collapsed, and advertising money needed afterwards to rebuild the position that the ranking was providing for free.
Order habitually above it and the cost is quieter but real — capital sitting in inventory, storage charges accruing, and a business that feels busy while being cash-poor. Since both errors are avoidable arithmetic, the discipline is simply to recalculate the point every season rather than setting it once and trusting it through changes in lead time and demand.
Setting it so it keeps working
Start from measured figures: average daily units, the true end-to-end lead time including production, freight, customs, and receiving, and a safety stock that reflects the variability you actually observe. Multiply the first two, add the third, and you have a trigger you can act on without re-deciding the question each time.
Then run it as a rule and revisit the inputs on a schedule — peak seasons lengthen both demand and lead times, and both changes push the reorder point upwards. Sellers who recalculate before the busy period avoid the annual pattern of scrambling in exactly the months they can least afford it.
In practice
A seller moving twenty units a day with a thirty-day end-to-end lead time and a hundred and fifty units of safety stock calculates a reorder point of 750. When stock reaches that level the order goes out, the new batch checks in as active inventory approaches the buffer, and the listing never goes offline — the ranking keeps climbing because the velocity never broke.
How Harpy Media helps
Replenishment planning is part of our operations work: reorder points built from measured lead times and demand, safety stock sized to real variability, and the trigger reviewed before each peak rather than after a stockout.
ROP FAQ
What is a reorder point?
The inventory level at which you should place a new purchase order — calculated as average daily sales multiplied by lead time, plus safety stock — so that replenishment arrives before current stock runs out.
How do I choose safety stock?
Size it from the variability you experience: how much demand swings and how unreliable the lead time is. Higher variability needs more buffer; the cost of the buffer should be weighed against the cost of a stockout.
Does the reorder point change?
Yes — recalculate it when lead times shift, when demand changes, and before peak seasons. A reorder point set once and never revisited drifts out of line with reality within a season or two.
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