I always choose PDF when exporting and usually choose JPG when saving. Being able to change the default format from PNG to either of these would save me a few clicks every time I use Preview. Is there a way? Preview preferences has no save/export format option, and I was unable to find anything on Google.

For bonus points, is there a way to have the default extension for images saved in JPG format with Preview be .jpg instead of .jpeg? It's a pain to change them manually every time, and leaving them means having to remember which files are .jpg (those not from Preview) and which ones are .jpeg (those from Preview) when making websites.

Thanks in advance.

  • Are you talking about screenshots, or something else? Normally, Preview will save an image in the same format that it came in as, unless you export it.
    – benwiggy
    Commented Jul 2, 2019 at 16:19
  • Hi, @benwiggy. For saving, I'm talking about new files. If I copy something into the clipboard, go to Preview and select "New from Clipboard", I can then save that file and it prompts me to choose a file format, but the default option is always PNG. For exporting, I normally have PNG files which I want to export as PDF files, but I don't like the "Export as PDF..." option because it adds white top and bottom margins, so I use "Export..."; again, the default format is always PNG (this might be simply because the original file is in PNG format; I haven't tested it).
    – Rain
    Commented Jul 2, 2019 at 16:28
  • Just tested the "Export..." menu item with a file originally in a format other than PNG; the default option was the file's format, not PNG. So I guess that's that. But the "Save" menu item still defaults to PNG, which is annoying.
    – Rain
    Commented Jul 2, 2019 at 16:30
  • For PDF: If you use "Export" (NOT Export As PDF) and then choose PDF as the file format, then you don't get the white margins. If the internet doesn't yield up a defaults write command to set the default format, then the method is probably unknown or non-existent!
    – benwiggy
    Commented Jul 2, 2019 at 17:00
  • Any reason you're copying and pasting, rather than opening the original item in Preview? If you want to save the contents of the clipboard to a PDF file, then I've made a python script that will do that. You can put it in the Scripts Folder and have it accessible from the menu bar. github.com/benwiggy/PDFsuite/blob/master/Shell_Scripts/…
    – benwiggy
    Commented Jul 2, 2019 at 17:06

1 Answer 1


Normally, Preview saves a document in whatever format the graphic image was imported. The only circumstance when a document in Preview has no pre-existing file format is when data is pasted from the clipboard.

There does not seem to be a known preference key for changing the default file format in Preview under this circumstance.

For me (on Mojave 10.14.5), Preview exports JPEG files as .jpg.

Both .jpg and .jpeg are valid file extensions, and there should be no difficulty in having both in a website. If you can't stand the chaos, you can easily batch process files in the Terminal with a script like this:

for file in *.jpeg; do mv "$file" "${file%.jpeg}.jpg"; done

which will work on all files in the current working directory.

  • Thanks for the Terminal snippet for the extensions; that certainly makes life easier. I hate chaos. Also, I believe I didn't explain my situation with websites clearly enough; it isn't that I can't use .jpeg with websites, but that if I have both .jpg files and .jpeg files then I need to know which images have which extension so I can call them properly in the HTML cod, which adds an extra step (checking file extensions) whenever I want to add an image.
    – Rain
    Commented Jul 11, 2019 at 20:52

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