The invention relates to a device for determining and/or positioning a sensor of a digital X-ray unit. The device includes an input and output unit, which serve to interactively control the device, and further includes a first storage location in which a digital picture of an area to be examined is stored. The device also includes a second storage location, in which at least one template-shaped image of the sensor is stored, and further includes a processing unit that simulatively places the template-shaped image of at least one sensor onto an area of the digital picture to be examined whereby completely displaying the area to be examined in the event of an actual X-ray picture.