Embodiments of gas mixing apparatus are provided herein. In some embodiments, a gas mixing apparatus may include a container defining an interior volume, the container having a closed top and bottom and a sidewall having a circular cross section with respect to a central axis of the container passing through the top and bottom; a plurality of first inlets coupled to the container proximate the top of the container to provide a plurality of process gases to the interior volume of the container, the plurality of first inlets disposed such that a flow path of the plurality of process gases through the plurality of first inlets is substantially tangential to the sidewall of the container; and an outlet coupled to the container proximate the bottom of the container to allow the plurality of process gases to be removed from the interior volume of the container.