What a scratch disk is and why Photoshop needs it

A scratch disk is temporary storage space on your hard drive that Photoshop uses when your computer's RAM runs out of room. Think of it like overflow parking: when your active memory is full, Photoshop writes data to the scratch disk to keep working. Without it, Photoshop would crash the moment you ran out of RAM.

The problem is that Photoshop doesn't always clean up after itself. Temporary files pile up, and eventually the scratch disk fills to capacity. When that happens, Photoshop slows to a crawl or stops working entirely. You'll see a message saying "Scratch disk is full" or notice that even straightforward edits take minutes to complete.

Clearing the scratch disk means deleting these temporary files so Photoshop has space to work again. You can do this while Photoshop is running, or you can dig into your hard drive and remove the files manually. The fastest method depends on whether Photoshop is currently stuck or responding normally.

Key Takeaways

  • Photoshop stores temporary data on your scratch disk when RAM fills up, and these files can accumulate until the disk is full.
  • The quickest fix is to use Photoshop's built-in purge function under Edit > Purge, which clears temporary memory without closing the program.
  • If Photoshop is frozen or unresponsive, restart the program and delete scratch disk files manually from your hard drive's temp folder.
  • On Windows, scratch disk files are usually in C:\Users\[YourUsername]\AppData\Local\Temp; on Mac, they're in /var/folders or ~/Library/Caches.
  • Preventing future buildup means checking your scratch disk space regularly and increasing the amount of RAM available to Photoshop.

Clear the scratch disk while Photoshop is open

If Photoshop is running and responding, the fastest way to free up space is to use the Purge function. Open Photoshop and go to the menu bar. Click Edit, then scroll down to Purge. You'll see four options: Undo, Clipboard, Histories, and All.

Click All to clear everything at once. This removes all temporary data Photoshop has stored, including undo history, clipboard contents, and cached information. Your document itself is not affected—only the temporary files disappear. After you click All, Photoshop will pause for a few seconds while it clears the space, then return to normal.

If you want to be selective, you can purge just the Undo history or Clipboard instead. Undo history often takes up the most space, so clearing that alone sometimes solves the problem. However, once you purge Undo, you can no longer undo previous edits in that session, so only do this if you're confident in your current work.

Restart Photoshop and delete scratch files manually

If Photoshop is frozen, unresponsive, or the Purge function doesn't free enough space, you'll need to close the program and delete scratch files from your hard drive directly. Close Photoshop completely—force-quit it if necessary. On Windows, press Ctrl+Alt+Delete, select Task Manager, find Photoshop, and click End Task. On Mac, press Command+Option+Escape, select Photoshop, and click Force Quit.

Once Photoshop is closed, navigate to the temporary files folder on your hard drive. On Windows, open File Explorer and type this path into the address bar: C:\Users\[YourUsername]\AppData\Local\Temp. Replace [YourUsername] with your actual Windows username. Look for folders named something like "Photoshop Temp" or files with names starting with "PST" or "~PS". Select these files and delete them.

On Mac, open Finder and press Command+Shift+G to open the Go to Folder dialog. Type /var/folders and press Enter. This folder contains temporary files for all programs. Look for Adobe or Photoshop-related folders and delete them. Alternatively, go to ~/Library/Caches (the tilde ~ means your home folder) and search for Adobe or Photoshop folders there.

After deleting the scratch files, restart Photoshop. It will rebuild its temporary storage from scratch, and you should have plenty of free space to work with.

Change which drive Photoshop uses as a scratch disk

By default, Photoshop uses your main hard drive (usually C: on Windows or Macintosh HD on Mac) as the scratch disk. If that drive is nearly full, you can tell Photoshop to use a different drive instead. This is especially helpful if you have an external hard drive or a second internal drive with more free space.

Open Photoshop and go to Edit (Windows) or Photoshop (Mac) in the menu bar. Click Preferences, then select Scratch Disks from the list on the left. You'll see your available drives listed with checkboxes. Uncheck your main drive and check a different drive that has more free space. You can assign multiple scratch disks if you want—Photoshop will use them in order.

Click OK and restart Photoshop for the change to take effect. From now on, Photoshop will store temporary data on the drive you selected. Make sure that drive has at least 10 to 20 GB of free space for comfortable working, especially if you edit large files or work with many layers.

Increase RAM to reduce scratch disk use

The root cause of scratch disk problems is usually insufficient RAM. If Photoshop is constantly writing to the scratch disk, it means your computer doesn't have enough active memory to handle your work. Adding more RAM is the most permanent solution, though it requires opening your computer or buying a new one.

Check how much RAM your computer currently has. On Windows, right-click This PC or My Computer and select Properties. On Mac, click the Apple menu, select About This Mac, and look for Memory. Most modern computers come with 8 GB, but Photoshop works much more smoothly with 16 GB or more, especially if you work with large files or many layers.

If you can't upgrade RAM, you can reduce how much memory Photoshop uses by closing other programs while you work. Each browser tab, email client, and background app consumes RAM. Closing them frees up more memory for Photoshop and reduces scratch disk strain. You can also reduce the number of undo steps Photoshop keeps in memory: go to Edit > Preferences > Performance and lower the History States number.

Monitor scratch disk space regularly

To prevent the scratch disk from filling up again, check your available hard drive space regularly. On Windows, open File Explorer, right-click your main drive, and select Properties. On Mac, click the Apple menu, select About This Mac, then click Storage. You want at least 15 to 20 percent of your drive to remain free at all times. If you're consistently below that, it's time to delete old files, move projects to external storage, or upgrade your drive.

You can also monitor Photoshop's memory use in real time. Go to Window in the menu bar and select Efficiency. This panel shows you how much RAM Photoshop is using and how much it's relying on the scratch disk. If the scratch disk percentage is consistently above 50 percent, you either need more RAM or need to work with smaller files.

Frequently Asked Questions

Will clearing the scratch disk delete my work?

No. The scratch disk only contains temporary data that Photoshop creates while you work. Your actual document is stored in memory and on disk separately. Clearing the scratch disk is like emptying a trash can—it removes only the temporary overflow, not your saved files or current project.

How often should I clear the scratch disk?

If you work with Photoshop regularly, clear it once a week or whenever you see the "Scratch disk is full" message. If you work with very large files or complex projects, you may need to clear it more often. Using the Purge function takes only a few seconds, so there's no harm in doing it frequently.

Can I delete scratch disk files while Photoshop is running?

No. Photoshop is actively using those files, so deleting them while the program is open can cause crashes or data loss. Always close Photoshop completely before manually deleting scratch files from your hard drive. The Purge function is safe to use while Photoshop is running because it tells Photoshop to release the files first.

What's the difference between clearing the scratch disk and emptying the Recycle Bin?

Clearing the scratch disk removes Photoshop's temporary files from the temp folder on your hard drive. Emptying the Recycle Bin removes files you've deleted from other programs. They're separate actions. You may need to do both to free up significant space, but clearing the scratch disk specifically solves Photoshop performance problems.

Why does Photoshop keep creating new scratch disk files?

Photoshop creates scratch disk files every time you work because it needs overflow storage when RAM fills up. This is normal behavior. The files should be cleaned up automatically when you close Photoshop, but sometimes they accumulate if the program crashes or closes unexpectedly. Regular purging prevents this buildup.