Exhaust-gas mixer

An exhaust-gas mixing pipe for admixing at least one additive into an exhaust-gas stream of an internal combustion engine, comprising:

• a housing wall of longitudinal axis L and of round cross section, and a closed end wall on which can be placed an injection nozzle, for said additive wherein the housing wall has multiple rows arranged over a circumference U, of openings, through which exhaust gas can flow from an outer side of the exhaust-gas mixing pipe into an interior of the exhaust-gas mixing pipe, wherein several openings of a row form in each case one stage M and wherein the respective stage M is characterized according to its size by an average opening cross section Q of its openings, wherein a sum of all the opening cross sections Q of all the openings of all the rows of the exhaust-gas mixing pipe is equal to SQ, wherein at least one first-order stage, stage M1, is provided, wherein the stage M1 has openings having an average opening cross section Q1, and an, in addition, at least one second-order stage, stage M2, is provided, wherein a stage M2 has openings having an average opening cross section Q2, where Q2≥f Q1, where 5≤f≤25, and there is provided a first sector S1 which is designed as a flushing sector and consists of at least the one stage M1, and a second sector S2 which is designed as a mixing sector and consists of at least the one stage M2, wherein, in the direction of the longitudinal axis L toward the end wall, the first sector S1 is positioned first and the second sector S2 is positioned thereafter.