Computer-implemented methods, systems, apparatus, and computer-readable media (transitory or non-transitory) are described herein for detecting eye tracking calibration errors. In various examples, respective poses of first and second eyes of a wearer of a head-mounted display ("HMD") may be determined. A portion of a first image rendered on a first display of the HMD may be selected based on the pose of the first eye of the wearer. The selected portion of the first image may be matched to a portion of a second image rendered on a second display of the HMD. An eye tracking calibration error may be determined based on the pose of the second eye of the wearer and a location of the portion of the second image.