Today’s Question: I realized that my primary hard drive was almost full, and I found that I had a large previews file for Lightroom Classic. Within the folder that contains my catalog I have a Previews lrdata file that is 79.9 GB. I also have a Smart Previews file that is 5.2 GB. I know I can build previews when I need them so how can I delete these previews to provide free space on my hard drive?
Tim’s Quick Answer: The Previews file associated with your Lightroom Classic catalog can simply be deleted if you need to recover storage space. For the Smart Previews file, you can actually use a command in Lightroom Classic to delete the Smart Previews for all photos within the catalog.
More Detail: The primary Previews file for the Lightroom Classic catalog is essentially just a cache and can be safely deleted at any time if you need to reclaim hard drive space. Just keep in mind that previews will need to be built again when you browse your photos, and those previews can only be built if the source files are available. So, for example, if you deleted the Previews file and keep your photos on an external hard drive, you would initially be unable to view the images until you connect the external hard drive. Once previews are built again you’ll be able to see photos even if the external hard drive is disconnected.
For the Smart Previews you can use the “Discard Smart Previews” command to delete Smart Previews for any photos you’d like (or for all photos in your catalog). For example, you could go to the All Photographs collection in the Catalog section of the left panel in the Library module and make sure the Library Filter Bar above the grid view is set to “None” so you’re browsing all photos. Then go to the menu and choose Library > Previews > Discard Smart Previews. Click the “Discard All” button, and the Smart Previews for all selected photos will be discarded.
Of course, as you browse your photos after discarding the standard previews, new previews will be generated. This may cause you to wonder whether it makes sense to delete the Previews file, since it will just get created again. However, unless you specifically direct Lightroom Classic to build previews for your entire catalog, previews will only be built as you browse photos. Therefore, the Previews file will be much smaller than it had been previously, and it may not grow all that quickly depending on your habits in terms of browsing photos.
