Replenishment / Reorder Point
Replenishment is the process of restocking inventory before it runs out. Your reorder point is the inventory level that triggers a new purchase order — calculated to ensure stock arrives before you sell out.
What is Replenishment / Reorder Point?
The reorder point (ROP) formula: ROP = (Average Daily Sales × Lead Time in Days) + Safety Stock. Lead time includes manufacturer production time, freight transit, and FBA check-in. Safety stock provides a buffer for demand spikes or supply delays — typically set at 14–30 days of expected sales.
For FBA sellers, the full replenishment cycle includes: placing the purchase order (1 day), manufacturer production time (2–4 weeks for reorders, longer for new products), quality inspection (2–3 days), booking and loading freight (3–7 days), sea freight transit (25–35 days China to US/UK), port clearance and inland freight (5–10 days), and FBA check-in and receiving (1–7 days). Total lead time: typically 60–80 days for imported products.
Inventory management tools like Inventory Planner, Skubana, and Cin7 automate ROP calculations based on real-time sales velocity from Seller Central API. They generate 'reorder now' alerts when inventory reaches the calculated ROP, preventing OOS events.
Why it matters for sellers
Every OOS event costs 3–5× the direct lost revenue when you account for rank recovery costs. Replenishment discipline — keeping each ASIN perpetually in stock — is the operational foundation of a healthy FBA business. Sellers who automate replenishment decisions and never stock out outperform manual operators by significant margins over 12+ month periods, both in revenue and in organic rank accumulation.
How to use Replenishment / Reorder Point
Set up Inventory Planner (or Cin7/Skubana) and connect to Seller Central. Review reorder alerts daily. For your top 5 ASINs by revenue, set a 90-day stock target rather than the minimum ROP — giving maximum buffer against supply chain disruptions.
Document your lead time per supplier accurately. If your manufacturer needs 21 days to produce a reorder and sea freight takes 32 days, use 60 days (production + freight + buffer) as your lead time input. Update this seasonally — freight times increase in Q4 when shipping lanes are congested.
Real-world example
A brand sells 45 units/day of their bestselling ASIN. Sea freight lead time from their supplier is 55 days. Safety stock target is 14 days. ROP = (45 × 55) + (45 × 14) = 2,475 + 630 = 3,105 units. When inventory at FBA hits 3,105 units, the system triggers a purchase order. The order arrives with ~14 days of buffer remaining. They have never gone OOS on this ASIN in 18 months of using this system.
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Frequently asked questions about Replenishment / Reorder Point
How much safety stock should I hold for Amazon FBA?
Minimum: 14 days of expected sales. Recommended: 21–30 days. For seasonal products during peak demand: 30–45 days. Safety stock should account for both supply variability (supplier delays) and demand variability (sales spikes). If your sales can double in a week during a promotion, your safety stock should accommodate at least one such event.
What is the difference between reorder point and minimum stock level?
Reorder point is the inventory level that triggers a purchase order, calculated to account for lead time and safety stock. Minimum stock level (or safety stock) is the buffer below which you never want to fall — the last-resort reserve. Your reorder point should be set above your minimum stock level. If your minimum is 300 units (safety stock) and your lead time demand is 1,200 units, your ROP is 1,500 units.
What tools automate Amazon replenishment planning?
Inventory Planner is the most widely used FBA replenishment tool — it connects to Seller Central, calculates dynamic reorder points based on sales velocity, and generates purchase order drafts. Skubana (now Extensiv) and Cin7 offer multichannel replenishment across Amazon, Shopify, and wholesale. For simpler setups, Helium 10's Inventory Management and Amazon's own Restock Inventory tool provide basic reorder point guidance.