What are Amazon storage fees?

Monthly charges for the warehouse space your FBA stock occupies.

Amazon charges FBA sellers monthly for the cubic space their inventory occupies, with higher rates in the last quarter of the year when warehouses are fullest. Stock that sits too long also attracts aged-inventory surcharges that step up with time.

Storage fees are why "it will sell eventually" is not a plan: a slow product quietly eats its own margin every month it sits. Watching per-product profitability over time - cost, fees and what actually sold - is how you catch the stock that should be repriced or cleared.