Why a stockout costs more than the sale
A stockout at launch does not just pause revenue — it surrenders rank. Position is earned through sustained sales velocity, and the marketplace reallocates that position the moment a listing goes unavailable. Winning it back is far more expensive than holding it, because a relaunch competes against sellers who never lost their momentum.
Treat available inventory as the thing that protects rank, not merely the thing that fills orders. The first run rarely fails because demand dried up; it fails because the reorder went in too late to matter.
Rank is rented, not owned
Every day out of stock is a day a competitor is handed the position you paid to earn.
Reorder on lead time, not units on hand
The common mistake is watching the stock that remains and reordering when it looks low. Reorder timing is set by total lead time — the full span between placing an order and having sellable inventory received and live. That span usually stacks several stages, each of which runs long:
Add these together and reorder while the first run still looks healthy. Waiting until stock looks low means the decision was already made too late.
Why early velocity misleads
Forecasting the reorder from opening sales overstates true demand. Launch velocity is inflated by launch advertising, promotions, and the ranking push that the initial spend buys. Project from that peak and the second order arrives too large.
Wait for enough operating history that demand settles after promotional support tapers, then forecast from the steady rate rather than the launch spike. Seasonality and promotions distort the signal further — strip known events out before reading the trend, or a holiday surge gets baked in as if it were the baseline.
The overstock mirror
Ordering too much is the opposite failure with a quieter cost. Excess inventory freezes capital in a warehouse that could have funded the next product, and aged stock accrues long-term storage charges that compound the longer it sits. Neither cost shows up as a missed sale, so overstock is easy to ignore until the balance sheet forces the issue.
Both directions have a cost
A stockout costs rank while an overstock costs capital and storage, so the reorder point is where you balance the two.
Setting the reorder point
Express the reorder point as a moment in lead time, not a quantity on the shelf. Trigger the next order when remaining coverage equals the total lead time, slip buffer included.
Revisit the reorder point every cycle. Lead times drift, suppliers change, and the settled rate ages as the listing matures.