Average point-source detection sensitivity of the eROSITA telescope as a function of the exposure time in the soft (red) and hard (blue) energy bands for the extragalactic sky. The horizontal dashed lines are the confusion limits for one source per 40 telescope beams (PSF HEW). The vertical line on the left shows the exposure time for a single scan at 100% observing efficiency, the other vertical lines indicate the average exposure times for different survey durations and at the ecliptic poles (for the soft-band confusion limit) at 80% observing efficiency.