Amazon-Only Inventory Management

You Do Not Need a Second Channel

Most inventory management tools are built for multi-channel sellers. Their marketing assumes you have Shopify and Amazon, or a website and a marketplace, or some combination. If you sell only on Amazon, you feel like you are paying for half a product.

We built ReplenishRadar to work for multi-channel sellers, yes. But the forecasting engine, the reorder logic, the PO generation, the FBA intelligence -- none of that requires a second channel. It works just fine with Amazon alone.

I want to be direct about this because I have talked to Amazon-only sellers who assumed they needed Shopify to get value from us. You do not.

The Amazon-Only Problem Set

Selling exclusively on Amazon has its own inventory challenges, and they are not simpler just because you have one channel.

FBA stockouts kill rankings. This is the big one. Stock out on your own website, you lose sales for a few days. Stock out on Amazon, you lose the buy box, your organic ranking drops, your PPC campaigns pause, and competitors grab your customers. Recovery takes weeks, not days. I have seen sellers lose 30% of their monthly revenue from a single 5-day stockout on a top ASIN.

IPI score pressure. Amazon grades your inventory health on a 0-1000 scale. Drop below their threshold (currently around 400) and your storage limits get cut. The IPI formula rewards balanced inventory -- not too much, not too little. Forecasting is the only way to thread that needle consistently.

Storage fees add up fast. The monthly storage fee is manageable. The aged inventory surcharge is not. Units sitting in FBA for over 181 days incur a surcharge on top of monthly storage. After 271 days, it gets worse. After 365 days, you are paying to store inventory that may never sell. I have seen sellers with $15,000 in annual aged surcharges -- nearly all avoidable with better demand planning.

Restock timing is unforgiving. Amazon's receive-and-stow process adds 5-14 days to your effective lead time. If your supplier ships in 21 days and Amazon takes 10 days to stow, your real lead time is 31 days. Miss that in your reorder calculation and you are guaranteed to stock out.

The Math That Matters

Here is a real scenario. You sell a product that moves 25 units/day on Amazon. Your supplier lead time is 30 days. Amazon's receive-and-stow takes about 10 days. You want 14 days of safety stock.

Reorder point = (daily velocity x total lead time) + safety stock

That is (25 x 40) + (25 x 14) = 1,000 + 350 = 1,350 units.

When your FBA inventory drops to 1,350, you need to have already placed a PO with your supplier. Not "start thinking about it." Already placed.

Now multiply that by 50 ASINs, each with different velocities and lead times. That is the spreadsheet from hell, and it needs to update every time velocity changes -- which is constantly.

ReplenishRadar runs this calculation on every sync cycle. Your reorder points stay current. When it is time to order, you get an alert with the specific quantity and the date by which you need to order.

What You Get as an Amazon-Only Seller

After connecting your Amazon account through the SP-API integration, the system starts pulling your FBA inventory, order history, and inbound shipment data. Within 24-48 hours, you have:

Demand forecasts per ASIN based on your actual sales history. The model picks up weekly patterns, monthly trends, and seasonal shifts. It does not assume your January looks like your July.

Reorder alerts that account for your total lead time -- supplier lead time plus the FBA receive window. These fire with enough runway to place the order and get units into FBA before you stock out.

FBA inventory monitoring across all fulfillment centers. You see total FBA units, inbound quantities, and days of supply at a glance. The stockout risk score tells you which ASINs need attention now versus next week.

Purchase order drafts grouped by supplier. When it is time to reorder, you are not starting from scratch. The PO is pre-built with quantities based on your forecast and your supplier's MOQ and casepack requirements.

Inbound plan creation through the SP-API. Select your items, confirm quantities, and ReplenishRadar creates the plan with Amazon directly. No logging into Seller Central, no copy-pasting MSKUs, no manual data entry. Amazon assigns fulfillment centers and you track progress without leaving the app.

Keeping Storage Fees in Check

The aged inventory surcharge is a tax on bad forecasting. If you send 2,000 units to FBA and only sell 800 in the next 6 months, you pay extra on those remaining 1,200 units every month past the 181-day mark.

ReplenishRadar's forecasts help you send the right amount. Not a guess, not "round up to be safe" -- a quantity based on your projected sell-through for the replenishment window. We would rather you send smaller, more frequent shipments to FBA than one large shipment that collects dust.

The system also flags inventory approaching the aged surcharge thresholds. You see which ASINs have units nearing 181 days, 271 days, and 365 days. That gives you time to run a promotion, create a removal order, or adjust your pricing before the surcharge hits.

Start a free trial -- connect your Amazon account and get your first forecasts within 48 hours.

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Learn More:

• Amazon FBA Restock Strategies - Timing your FBA replenishment
• FBA Long-Term Storage Fees - How to avoid the aged inventory surcharge
• Amazon FBA Inventory Tools - Full feature overview for FBA sellers
• Compare ReplenishRadar to SoStocked - Amazon tool comparison