A magazine loader for automatically loading stacks of cartons onto a magazine of a mass feeder for supplying cartons to a packaging machine, includes a loader in which stacks of cartons are received and held, and a carriage on which the loader is pivotally mounted. The cartons are received loaded in the loader, after which the loader is pivoted from a loading position to a stacking position. The loader is then moved along a feeder conveyor for the packaging machine toward a magazine or supply of previously stacked cartons, until the stack of cartons is received and stacked against the previously loaded cartons to maintain a supply of cartons for feeding into the packaging machine.