A stacker includes a base and a vertical structure supported by the base. A lift unit includes a support surface for engaging and lifting a tray from a stack of trays. The lift unit is mounted to the vertical structure and movable vertically relative to the vertical structure. A lifting mechanism selectively raises and lowers the lift unit relative to the vertical structure. The support surface may be formed on first and second projections configured to engage first and second handle openings of a tray. The stacker facilitates several stacking/destacking methods for more easily converting a stack of trays at a first height to a stack of trays at a second height. For example, the first height may be more convenient or appropriate for use in a bakery, while the second height may be more efficient for loading in a truck.