"How much to stock this time?" is cross-border sellers' most frequent and hardest question. By feel, it's often either stockout or overstock. Back-calculating by "turnover days" is steadier.
Three inputs
- Average daily sales: take the 30-day mean, strip anomaly days
- Replenishment cycle: days from order to sellable (head freight + inbound + shelving)
- Safety factor: the more volatile the sales, the higher the factor (e.g., 1.2–1.5)
Formula
Safety stock ≈ average daily sales × replenishment cycle × safety factor
Reorder point ≈ average daily sales × replenishment cycle
When sellable drops below the reorder point, it's time to order.
Why it works
It quantifies "afraid of stockout" and "afraid of overstock" into a number, not emotion.
Stocking is essentially finding a dynamic balance between stockout risk and storage cost.
Different SKUs use different factors: higher for hot items, lower for long-tail. Make it a weekly habit and inventory flows better.