Inventory synchronization between Amazon and other marketplaces is not immediate. Although most updates complete within a few hours, the official synchronization window is 24–48 hours and depends on marketplace processing.
What This Means
Most inventory updates complete within 3–5 hours.
Amazon and eBay determine how quickly inventory updates are processed.
During the synchronization window, there is a possibility of duplicate sales if an item sells on one marketplace before the inventory update reaches the other.
Best Practices
Monitor inventory regularly.
Keep inventory quantities accurate.
Be aware of the synchronization window when selling across multiple marketplaces.
Contact support if inventory updates consistently exceed the normal processing timeframe.