I'm pretty sure that's not possible. They'll probably have to be recreated.
In the Custom Page Size dialog box, there are buttons to Add or Delete page sizes. If that information could be stored externally, there would Export and Import buttons and a file format to store the information. But those buttons are not there.
That's what I was thinking, but before I started recreating I figured I'd ask. Thanks for your feedback!
Yes you can, but you need to do it a little bit tricky. But that's not too hard.
If you are using Mac OSX just follow this simple steps.
Quit Adobe InDesign CC or Adobe InDesign CS6 if they are currently opened.
1. Go to folder
HD -> Users -> Username -> Library -> Preferences -> Adobe InDesign
Note: You need to unhide the "Library" folder since by default it is hidden.
2. You can see different folder named "Version XX"
Open the folder named Version 8.0 -> en_US ->
Copy "InDesign Defaults"
Also copy the folder "Page Sizes" if you created a Custom Page Size that you did not save as Document Preset
3. Go to folder
Version 9.0 (Backup your Adobe CC InDesign Defaults. Ex. Renaming them into InDesign Default (Backup)
Paste the the file you copied from your Version 8 folder
"InDesign Defaults" and "Page Sizes"
4. Open up Adobe InDesign CC, the open up File -> New.
There you have all your document preset and document custom size.
If you are using Microsoft Windows 7 or 8
The location of Adobe InDesign Preference is
My Computer -> Local Disk -> [hidden folder] Program Data -> Adobe InDesign
I would suspect to long-term success of replacing a newer version of InDesign preferences (which is what InDesign Defaults is) with the older version of ID preferences. People have run into a lot of problems trying to import keyboard shortcuts or workspaces from older versions. It may work in the short term, but cause more problems in the long term.
What you can do is to load Master page from an older document. These master pages can have different page sizes too.
Good suggestion, Willi!
In new versions of InDesign is new function SYNC of user setting, but CUSTOM page sizes are not included. Unbelievable... :/
Page sizes are not a part of preferences, they are part of a specific document. You can load masters from other documents as you can do with styles or colors too. SO it is correct.
roenoz : thanx, copying "Page Sizes" (contains one file "New Page Sizes.xml") to new version works
Its really simple, but I still don't understand why I should care about thinks like this.. InDesign is a legend, expensive program, this is weird.
Put this feature in to Sync option should be for InDesign DEVELOPERS peace of cake.
I created a feature request and start dist discussion: Whish list: Sync also "custom" page sizes. Pleeease.