Methods and systems for inventory planning are described. An inventory reduction factor for an entity, based at least in part on an estimated ability of hosted merchants to fulfill demand for an item, may be determined. An adjusted target inventory estimate may be calculated using the determined inventory reduction factor and a target inventory quantity. The hosted merchants may be merchants offering the item for sale via a sales channel through which the entity also offers the item. The hosted merchants may in some cases be merchants offering the item for sale via the entity's website.