Running out of stock on Amazon is one of the most damaging events for your seller account. Stockouts cause your Best Seller Rank (BSR) to drop, your keyword rankings to fall, and your advertising costs to spike when you relaunch.
This guide teaches you a proven inventory replenishment system that keeps your Amazon FBA stocked — without over-ordering.
Why Inventory Replenishment Matters
The Cost of Stockouts
| Impact | Description |
|---|---|
| Lost sales | Every day out of stock = lost revenue (avg. $50–$200/day per ASIN) |
| BSR drop | Ranking can fall 50%+ within 3–5 days of stockout |
| Keyword ranking loss | Organic search positions drop; hard to recover |
| PPC cost increase | After relaunch, ad costs spike 2–3x to regain ranking |
| Buy Box loss | If you're the only seller, Buy Box disappears; if shared, you lose it |
| IPI score impact | Stock history affects your Inventory Performance Index |
The Cost of Overstocking
| Impact | Description |
|---|---|
| Long-term storage fees | $0.15–$6.90 per cubic foot per month (181+ days) |
| Capital tied up | Cash locked in inventory that isn't selling |
| Aged inventory surcharge | Additional 5%–10% fee on inventory 271+ days old |
| Storage limits | Amazon may reduce your storage allowance |
The goal: Order the right quantity at the right time — not too much, not too little.
Understanding Amazon's Inventory Metrics
Key Metrics to Track
| Metric | What It Means | Target |
|---|---|---|
| Days of Supply | How many days your current inventory will last | 30–45 days |
| Sell-Through Rate | Units sold ÷ units in stock (over 30 days) | >10% |
| Excess Inventory | Units with 90+ days of supply | <10% of inventory |
| Stranded Inventory | Units at FBA but not listed for sale | 0 |
| IPI Score | Amazon's overall inventory health score | >500 (ideally >700) |
| Replenishment Rate | How quickly you restock after selling | Within lead time |
Amazon Inventory Performance Index (IPI)
Your IPI score determines your storage limits:
| IPI Score | Storage Limit Impact |
|---|---|
| 0–399 | Restricted storage; potential quarter-over-quarter limits |
| 400–499 | Standard storage limits |
| 500–699 | Good standing; flexible limits |
| 700+ | Excellent; maximum flexibility |
How to Calculate Your Reorder Point
Your Reorder Point (ROP) is the inventory level at which you should place a new order with your supplier.
Formula
Reorder Point = (Average Daily Sales × Lead Time in Days) + Safety Stock
Definitions
- Average Daily Sales: Total units sold in last 30 days ÷ 30
- Lead Time: Total days from placing order to FBA receiving (production + shipping + receiving)
- Safety Stock: Buffer inventory to handle unexpected demand spikes or shipping delays
Example Calculation
Let's say you sell a kitchen gadget:
| Variable | Value |
|---|---|
| Monthly sales (30 days) | 600 units |
| Average daily sales | 600 ÷ 30 = 20 units/day |
| Production time | 10 days |
| Sea freight time (LCL) | 30 days |
| FBA receiving time | 5 days |
| Total lead time | 45 days |
| Safety stock (7 days) | 7 × 20 = 140 units |
Reorder Point = (20 × 45) + 140 = 900 + 140 = 1,040 units
→ When your FBA inventory drops to 1,040 units, place a new order immediately.
How to Calculate Reorder Quantity
Your Reorder Quantity (ROQ) is how many units to order each time.
Formula
Reorder Quantity = (Average Daily Sales × Reorder Cycle) + Safety Stock - Current Inventory
Example Calculation
| Variable | Value |
|---|---|
| Average daily sales | 20 units/day |
| Desired reorder cycle | 60 days (order every 2 months) |
| Safety stock | 140 units |
| Current inventory (at reorder point) | 1,040 units |
Reorder Quantity = (20 × 60) + 140 - 1,040 = 1,200 + 140 - 1,040 = 300 units
Wait — that doesn't seem right. Let's recalculate:
Actually, reorder quantity should cover the next reorder cycle:
Reorder Quantity = Average Daily Sales × Reorder Cycle = 20 × 60 = 1,200 units
The safety stock is already built into your reorder point. So you order enough to last until the next reorder.
Choosing Your Reorder Cycle
| Reorder Cycle | Pros | Cons | Best For |
|---|---|---|---|
| 30 days | Low capital tied up; fresh inventory | Frequent ordering; higher per-unit shipping cost | New products, low-volume sellers |
| 60 days | Balanced; moderate shipping costs | Moderate capital commitment | Established products |
| 90 days | Lowest per-unit cost; FCL possible | High capital; risk of excess inventory | High-volume, stable sellers |
Lead Time Management
Typical Lead Time Breakdown
| Stage | Sea Freight (LCL) | Air Freight |
|---|---|---|
| Order placement to production start | 1–3 days | 1–3 days |
| Production | 7–15 days | 7–15 days |
| Quality inspection | 1–2 days | 1–2 days |
| Labeling & packaging | 1–3 days | 1–3 days |
| Freight transit | 25–35 days | 5–10 days |
| Customs clearance | 2–5 days | 1–3 days |
| FBA receiving | 2–5 days | 2–5 days |
| Total lead time | 39–68 days | 19–41 days |
How to Reduce Lead Time
- Maintain standing orders: Keep your supplier producing continuously — they'll prioritize your orders.
- Pre-order packaging materials: Have cartons, poly bags, and labels ready before production finishes.
- Use air freight for urgent restocks: Cuts 20–30 days off lead time.
- Use a China warehouse: Store finished products at your forwarder's warehouse in China, ready to ship when needed.
- Pre-clear customs: Provide documents early for pre-clearance processing.
Seasonal Replenishment Strategy
Amazon Seasonal Calendar
| Season | Peak Period | When to Ship | Recommended Method |
|---|---|---|---|
| Q4 Holiday | Nov 1–Dec 25 | By Aug 15 | Sea freight (ship by July) |
| Prime Day | July (mid-month) | By May 15 | Sea freight (ship by April) |
| Back to School | Aug 1–Sep 15 | By June 1 | Sea freight (ship by May) |
| Spring Sale | March–April | By Jan 15 | Sea freight (ship by Dec) |
| Chinese New Year | Jan/Feb (factory closure) | Stock up before CNY | Sea freight + air freight |
Seasonal Stock-Up Strategy
For Q4 (the biggest sales season):
| Timeline | Action |
|---|---|
| June | Forecast Q4 demand (2–3x normal volume) |
| July | Place production order with supplier |
| August | Ship by sea freight (must leave China by Aug 15) |
| September | Shipment in transit; prepare PPC campaigns |
| October | Shipment arrives at FBA; inventory goes live |
| November | Peak sales begin; monitor inventory daily |
| December | Last-minute air freight if running low |
Tools for Inventory Management
| Tool | Price | Best Feature |
|---|---|---|
| Amazon Seller Central | Free | Built-in inventory dashboard, restock recommendations |
| Helium 10 | $79–229/mo | Inventory levels, reorder alerts, profit calculator |
| Jungle Scout | $49–129/mo | Sales estimates, inventory tracker |
| SellerBoard | $15–50/mo | Profit analytics, stock alerts |
| Forecastly | $35–150/mo | Demand forecasting, reorder suggestions |
| Google Sheets | Free | Custom inventory tracking (if you're just starting) |
Common Replenishment Mistakes
| Mistake | Fix |
|---|---|
| Ordering too late | Set reorder alerts at 45 days of supply |
| Ignoring seasonality | Build seasonal forecasts into your reorder plan |
| Forgetting CNY factory closures | Stock up 45 days before Chinese New Year |
| Not accounting for production time | Include 10–15 days of production in lead time |
| Over-ordering new products | Start with small test orders; scale based on data |
| Not tracking IPI score | Check monthly; fix stranded/excess inventory |
| Relying on one shipping method | Have air freight as backup for delays |
Need Help Shipping From China?
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Request a QuoteFAQ
Q: How much inventory should I keep at Amazon FBA? A: Maintain 30–45 days of supply at FBA at all times. This gives you enough buffer to place a new order and receive it before running out.
Q: How do I know when to reorder? A: Set a reorder point = (average daily sales × lead time) + safety stock. When FBA inventory drops to this number, place a new order immediately.
Q: What happens if I run out of stock on Amazon? A: Your BSR drops, keyword rankings fall, and you lose the Buy Box. When you relaunch, PPC costs will be 2–3x higher to regain ranking. Avoid stockouts at all costs.
Q: Should I use Amazon's automated replenishment? A: Amazon's "Supply Chain by Amazon" and AGWA programs can automate replenishment, but they may not always be the cheapest option. Compare with your own freight forwarder's rates.
Need Reliable Restocking?
Skyler Logistics helps Amazon sellers maintain seamless inventory replenishment with scheduled shipping from China. We offer flexible shipping schedules, China warehouse storage, and real-time tracking.
📦 Contact us at skylerlog.com — never run out of stock again!
