Select Edit > Catalog Settings (on Windows) or Lightroom Classic > Catalog Settings (on macOS).
Last updated on
Oct 27, 2025
Learn how to create sidecar files like XMP and ACR to save metadata.
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Automatically save metadata
Select Metadata and select Automatically write changes into XMP to save metadata automatically. When you select Automatically write changes into XMP, Lightroom continuously saves your edits as you work on your images.
Manually save metadata
Select a photo in the Library or Develop module.
Select Photo > Save Metadata to File.
In the Save metadata to file dialog box, select Continue.
Verify sidecar files
Once you have saved the metadata automatically or manually, Lightroom will create a sidecar file to store it. If heavy edits are applied to an image, Lightroom will create an XMP and an ACR file to store the metadata.
In the Library module, select the photo for which you want to verify the sidecar files, then select Metadata.
Verify the created sidecar files in the Sidecar Files field.
Frequently asked questions abour XMP and ACR sidecar files
- What is an ACR sidecar?
Lightroom supports storing metadata in external sidecars for Raw images and a few non-raw image formats. This is usually in the form of an XMP sidecar file (Extensible Metadata Platform ) that is created and saved along with the native image. An ACR sidecar (Adobe Camera Raw sidecar) is also an external sidecar file with an .ACR file-type extension. It resides next to the original asset and can hold metadata changes related to the image.
- What changes are introduced with Lightroom Classic (version 15.0)?
Starting with Lightroom Classic (v 15.0), Lightroom creates and maintains an additional ACR sidecar when storing metadata in sidecars. This capability intends to reduce the size of the XMP sidecar and minimize catalog bloating, significantly reducing the catalog size (.lrcat) for Lightroom customers.
- When is an ACR sidecar created?
Starting with the Lightroom Classic (v 15.0) release, Lightroom identifies if there are any heavy edits, masks, or AI settings like Super Resolution, Distraction Removal, and Denoise. It writes the heavy edits to the ACR sidecar while keeping the XMP sidecar lightweight. If there aren't any heavy edits, Lightroom will continue writing metadata changes to the XMP sidecar. The writes to sidecars continue to happen whenever the metadata is saved (via Metadata preference). Lightroom also maintains the lifecycle of all sidecars when it's used to move/rename/delete the image.
- How does this change impact Lightroom users?
With the introduction of ACR sidecars, the traditional XMP sidecar benefits from size reduction. This also reduces the catalog size, especially for images with heavy edits, as the catalog (.lrcat) correlates heavily with the contents of the XMP sidecar.
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