Excess inventory on Amazon FBA refers to stock sitting longer than needed (typically >90 days supply), leading to higher storage fees, aged inventory surcharges, and reduced IPI scores.
It's FBA stock exceeding forecasted demand for the next 90+ days. Amazon flags it in the Inventory Performance dashboard and applies surcharges (especially for items aged 181+ or 365+ days).
Compares current stock to predicted sales velocity. Anything over 90 days' supply counts as excess; older stock (271+ days) faces escalating fees.