Abstract: A gas mixing device for linearizing or calibrating a gas analyzer. The gas mixing device includes a first gas inlet line for a first gas, a second gas inlet line for a second gas, a mixing channel having inlet openings which are arranged one behind the other in a flow direction, the inlet openings comprising a first upstream inlet opening and a second downstream inlet opening, and at least two valves which each comprise at least one inlet and one outlet. The at least two valves release or block a fluidic connection between at least one of the first gas inlet line and the second gas inlet line, and the mixing channel via the inlet openings. A flow cross section of the mixing channel is smaller at the first upstream inlet opening than at the second downstream inlet opening.