Maximize Compatibility: what it stores and when to turn it off

Updated October 8, 2026

When you save a layered file in Adobe Photoshop with Maximize Compatibility on, Photoshop stores a second copy of your picture inside the file: all the layers flattened into one full-size image. The copy is there for other apps. Photoshop itself doesn't use it when it opens a layered file, because it builds the picture from your layers.

In our tests it was the largest single thing we could remove without losing any work: a quarter of the space across 34 public Photoshop files. This guide explains what the copy is for, which apps need it, and how to take it out of files you've already saved.

What Maximize Compatibility stores

Maximize Compatibility, sometimes called "maximum compatibility," is a preference in Photoshop's File Handling settings, called "Maximize PSD and PSB File Compatibility" there. With it on, every save writes a composite image at the document's full size and bit depth, after the layers. Adobe describes it as a flattened version of the image for "older versions of Photoshop or applications that don't support layers," and adds that it "maintains the appearance of the document, just in case future versions of Photoshop change the behavior of some features" (Adobe's file formats help).

So the purpose of the setting is to let an app that can't read Photoshop layers, or can't draw every layer feature, still show the finished picture. The file needs a picture in that slot either way: with the option off, Photoshop writes a white image of the same size there, which compresses to almost nothing, and marks the file as having no real flattened copy. Your layers, masks, smart objects and effects are saved the same way in both cases.

When Photoshop opens a layered file, it draws the picture from the layers and ignores the stored copy. That's why turning the option off changes nothing you see in Photoshop. We checked this on 42 files: with the copy removed, Photoshop 2026 showed the same layers and identical pixels in every one.

How much space it adds

The flattened copy is one image the size of your canvas, so it costs about as much as one full-canvas layer. A file with a single painted layer comes close to doubling. A file whose bulk is in hundreds of layers or in large smart objects pays a much smaller share. Here are published tests next to ours:

Photographer and author Tim Grey puts it more simply: an image with a Background layer and some adjustment layers comes out about twice as large with the option on. Adjustment layers hold almost no pixels, so the flattened copy is about the size of the whole Background.

Bit depth matters too. Photoshop already compresses 16 and 32-bit layers well, so in 16-bit files the flattened copy is where most of the removable space is. In 8-bit files the layers themselves have room to shrink as well, which our guide on every way to reduce PSD file size covers.

Which apps need it

Why should you maximize PSD and PSB file compatibility at all? Mostly for other apps, plus one recovery trick in Photoshop.

Adobe Lightroom Classic is the clearest case: it won't import a layered PSD or PSB without the copy. Adobe's help says such a file "must be saved in Photoshop with the Maximize PSD and PSB File Compatibility preference turned on" (Lightroom Classic supported formats).

Adobe InDesign and Illustrator can rely on it when you place a PSD. In an Adobe Community thread on the setting, one reply reports errors placing files saved without it in both apps, and the accepted answer explains that apps which display a layered PSD through its composite show it blank, or can't import it, when the composite is missing. File browser previews may come up blank too, since some of them read the same copy.

Apps that read the layers themselves don't need it. Photoshop is one. GIMP 3 and Krita 5.3 are others, and in our tests they showed our files the same with the copy removed. For any other app, test one file before you change a whole folder.

The recovery trick: if a file's layer data is ever damaged, one of the steps in Adobe's guide to recovering damaged Photoshop files is to open just the flattened copy. Adobe notes it only works if the file was saved with Maximize Compatibility on, and what you get back is a flat picture without your layers. For a file with no backup, that can still be worth having.

Should you turn it off?

Turn it off if your PSDs only ever go back into Photoshop, you keep backups, and you care about disk space or save time. Leave it on if Lightroom Classic, InDesign or Illustrator ever read your files, or if you hand PSDs to people and don't know what they open them with. Adobe's own performance guide suggests Ask or Never to speed up saving, and notes that Never "reduces file size and saves time, but prevents older applications from opening your files." Tim Grey takes the other side and recommends leaving it on if you might ever use your files outside Photoshop or Bridge.

The three choices in the menu work like this:

• Always writes the flattened copy on every save. Pick it if any of your files go to Lightroom Classic or a layout app.
• Never leaves it out. Pick it if your files stay in Photoshop.
• Ask shows a checkbox each time you save a layered file, for when it depends on the file.

How to turn it off

1. Open Photoshop > Preferences > File Handling on a Mac, or Edit > Preferences > File Handling on Windows.
2. Set "Maximize PSD and PSB File Compatibility" to Never.
3. Click OK.

The setting only affects future saves. Files already on your disk keep their flattened copy until something rewrites them.

Removing it from files you already saved

This is where most advice stops. The owner of an archive of tens of terabytes, all saved with the option on, asked on the Adobe forums how to get the space back (batch remove Maximize Compatibility from PSD folders, August 2025). An action that re-saved each file with the preference off didn't shrink them. There are three ways that do work.

Re-save each file in Photoshop

Open the file in Photoshop and save it with the preference set to Never. The accepted answer in that thread is a script by Stephen Marsh that does this for a whole folder tree: it sets the preference to Never, opens every PSD and PSB, adds and removes a temporary layer, saves over the original and restores your preference. It works, and the thread warns to run it on copies, since it overwrites every file. Each file also has to open and save in Photoshop, which takes as long as it normally would.

The white-layer trick

The most common tip online is to add a white or solid-color layer on top, or hide every layer, and save. The flattened copy then becomes a flat color that compresses to almost nothing. In the Creative Market reader's test it saved about as much as turning the option off (182.6 MB against 180.8 MB). The catch is an extra layer you have to delete before working on the file again, and previews of the file show a white or empty square.

Layersqueeze

Layersqueeze's "Drop the flattened copy" step writes the same blank image and the same "no real flattened copy" flag that Photoshop writes when the option is off. Alpha and spot channels, which are stored in that part of the file, stay. It runs in your browser, doesn't need Photoshop, never uploads your file and never changes the original: you download a new copy, which it has already read back and compared with the original, layer by layer.

It also stores 8-bit layers with zip compression, something Photoshop doesn't offer for 8-bit files. That's why our Sol Levante painting went from 58.7 MB to 19.6 MB with Layersqueeze, against 36.5 MB when Photoshop re-saved it with the option off.

Two limits to know. First, Layersqueeze suits files you've finished. If you open the smaller copy and save it in Photoshop again, Photoshop rewrites the whole file its own way: our example went back to 58.7 MB with the option on, or 36.5 MB with it off. To keep files small while you're still working on them, set the preference to Never; use Layersqueeze for archives, backups and files you send. Second, it works in a browser tab a few files at a time, and files over about 1 GB may not fit in the tab's memory, so for a multi-terabyte archive the script above is still the practical route today.

If you import files into Lightroom Classic, untick "Drop the flattened copy" before you drop them on the page. You still get the zip saving. And if you plan to replace your originals with the smaller copies, remember that you give up the recovery trick above, so keep a backup of anything you couldn't redo.

Putting it back

If you later need the flattened copy, for example to bring a file into Lightroom Classic, open it in Photoshop with the preference set to Always (or tick Maximize Compatibility in the save dialog if it's set to Ask) and save. Photoshop writes the copy again, and the file returns to about its old size.

For many files at once, use File > Scripts > Image Processor, tick Save as PSD and its Maximize Compatibility box. It saves new copies in a folder called PSD and doesn't overwrite the originals (Adobe's Image Processor help). Tim Grey describes the same steps for fixing PSDs that Lightroom Classic won't import.

If you're not sure the flattened copy is your problem, our guide to why PSD files get so big covers the other causes.