Today’s Question: My computer has been sending me urgent distress signals, telling me that I need to free up hard drive space ASAP. My Lightroom previews.lrdata file is 58GB and contains only standard previews. My photos reside on an external HD. Can I safely delete the previews file to free up space on my computer? What would you recommend?
Tim’s Quick Answer: Yes, it is safe to delete the Lightroom Classic previews file. However, this will slow performance in Lightroom Classic, and over time the previews file will grow as new previews are built for your photos.
More Detail: Lightroom Classic builds lower-resolution JPEG previews of your original captures to speed up the process of browsing your photos. Those previews are stored in a previews file, which has the same base filename as your Lightroom Classic catalog file, with “Previews” appended to that name and a filename extension of “lrdata”. It is safe to delete this file if you need to recover hard drive space, as the previews can always be re-built later.
Deleting the previews file can certainly free up considerable storage space. Of course, this would generally be a temporary fix, since the next time you launch Lightroom Classic, previews will be built again for images in each folder (or other location) that you actually browse. Therefore, even if you need to delete the previews file temporarily, I would also look for other files that can be deleted in order to free up more hard drive space.
Later, once you have adequate storage space, you could build previews for all images in your catalog. To do so, first navigate to the All Photographs collection in the Catalog section of the left panel in the Library module. Then make sure there are no filters set so that you’re actually browsing all images, and then choose Edit > Select All from the menu to select all of the photos. Finally, from the menu, select Library > Previews > Build Standard-Sized Previews.
Another option would be to move the entire folder containing your Lightroom Classic catalog and related files to an external hard drive, in order to free up space on your internal hard drive. Keep in mind, however, that having the catalog on an external hard drive will degrade performance in Lightroom Classic, so it is best to keep the catalog on the internal hard drive of your computer if at all possible.