The present invention relates to a device for fitting and determining the size of a patient interface, said device (10) comprising a sizing gauge(12), wherein the shape of the gauge (12) is configured to replicate the shape of a contacting surface of a patient interface with the portion of a patients face, and a support (14) including a grip (16) for holding the device (10) by hand during use, which support (14) is mechanically coupled to said gauge (12).
