Quick answer: Amazon FBA available inventory is sellable and ready to ship. Reserved inventory is temporarily unavailable due to customer orders, transfers, or processing. Inbound inventory is moving through a shipment workflow. Unfulfillable inventory is at Amazon but not sellable. Stranded inventory is physically present without an active buyable offer. Total inventory should never substitute for available inventory when calculating stock coverage.
Amazon can physically hold 500 of your units while only 320 are available for customers to buy. That's not automatically a missing-inventory problem. The remaining units may be inbound, reserved, transferring, processing, unfulfillable, or stranded. Each status answers a different question.
The inventory-status table
| Status | Can a customer buy it now? | Typical cause | Seller action |
|---|---|---|---|
| Available | Yes | Sellable stock ready to fulfill | Monitor coverage and velocity |
| Reserved | Not currently | Customer order, FC transfer, FC processing | Review sub-status and duration |
| Inbound | Usually not yet | Shipment working, shipped, receiving, or being processed | Track shipment and receiving progress |
| Unfulfillable | No | Damage, defect, or non-sellable condition | Choose removal, disposal, or a permitted recovery action |
| Stranded | No | No active offer, or a listing/account issue | Fix the stranded reason quickly |
Available inventory
Available is the number that matters most for immediate customer demand, the quantity Amazon can ship to customers right now. If a product sells 10 units a day and shows 50 available units, it has roughly five days of immediately sellable FBA stock, even if another 200 units appear elsewhere in the network. This is the conservative starting point for days-of-inventory calculations.
Reserved inventory
Reserved doesn't mean one thing. Amazon's Reserved Inventory report can break the quantity into operational causes: units connected to customer orders or order processing, units Amazon is moving between fulfillment centers, and units under receiving, inspection, or preparation. A sudden increase in reserved stock can make an ASIN look healthy in total while the buyable quantity falls, which can slow the delivery promise or contribute to a stockout.
Inbound inventory
Inbound is stock being sent to Amazon or processed through receiving, with stages commonly labeled working, shipped, in transit, delivered, checked in, and receiving. Inbound units shouldn't all be treated as equally reliable. A shipment that hasn't left the warehouse is not the same as a shipment receiving at Amazon, and a shipment receiving at Amazon is still not the same as available inventory. For planning, assign confidence: working shipment is low confidence, carrier-confirmed in transit is medium confidence, checked in or receiving is higher confidence, and available is fully usable for current demand.
Unfulfillable inventory
Unfulfillable stock is at an Amazon fulfillment center but can't currently be sold. Amazon may classify units as customer damaged, warehouse damaged, defective, or carrier damaged depending on the event and marketplace. The seller should inspect the disposition reason, reimbursement eligibility, whether the unit can be refurbished, and removal or disposal deadlines. Unfulfillable quantity isn't merely a warehouse-cleaning task, it can be a product-quality signal. If a glass item repeatedly becomes warehouse damaged, packaging deserves investigation.
Stranded inventory
Amazon defines stranded inventory as FBA stock without an active offer. The units exist, but customers can't buy them, common causes include a closed listing, a pricing error, a restricted product or compliance issue, listing suppression, or an account issue. Stranded inventory deserves urgency because it creates the worst combination: storage cost without a sales opportunity. Fix the cause rather than creating duplicate listings; the Stranded Inventory report should identify the reason and available action.
Why "received" does not always mean "available"
A seller sends 400 units to FBA before a seasonal event. The shipment page shows the units have been received, so advertising increases. Only 110 units become available; most of the remainder moves into FC transfer. Ads accelerate demand against the 110 available units and the ASIN stocks out before the transferred units return to availability. The error wasn't trusting Amazon, it was using a shipment milestone as a sellable-stock number. Received means Amazon acknowledged units in the inbound process. Available means Amazon can offer them for fulfillment now.
The correct inventory equation
For immediate coverage: immediate days of stock equals available units divided by daily unit velocity. For planning coverage: planning stock equals available plus selected reserved plus confidence-weighted inbound. Don't add every reserved and inbound unit at 100%.
Example: available is 120, reserved customer order is 20, FC transfer is 80, receiving is 100, shipped but not checked in is 200, and daily velocity is 10. Immediate coverage is 12 days. A careless total says 52 days. A realistic plan treats the customer-order units as already committed, the FC transfer and receiving units as probable but not immediate, and the shipped units as uncertain until receiving progresses.
When reserved inventory becomes a problem
Reserved stock is normal. Investigate when the quantity is unusually high relative to available stock, units remain in the same sub-status longer than expected, the ASIN is approaching a stockout, a transfer blocks a seasonal launch, or the quantities don't reconcile across the Reserved Inventory report and the FBA Inventory page. Open a case with SKU, FNSKU, ASIN, quantity, sub-status, shipment or order references, dates, and screenshots.
An operating dashboard should separate available stock from broad FBA quantity, and EcomSanity uses FBA inventory with sales velocity to surface low-stock risk. The useful behavior isn't showing the biggest inventory number, it's warning when sellable stock and actual demand no longer match. For what to do once that gap turns into a real stockout, see the Amazon stockout recovery plan.
Frequently asked questions
What does reserved mean in Amazon FBA?
Reserved units are temporarily unavailable because they're linked to customer orders, fulfillment-center transfers, or fulfillment-center processing. Use the Reserved Inventory report to see the breakdown by sub-status.
Does reserved inventory count as in stock?
It exists in the network, but it isn't currently available for immediate customer fulfillment. Treat it separately in stock-cover calculations rather than adding it to available units at full value.
What is stranded inventory on Amazon?
FBA stock without an active offer. The units physically exist, but customers can't buy them because of a closed listing, pricing error, compliance issue, or suppression. Fix the underlying cause rather than creating a duplicate listing.