How do I make everything bigger in JOSM?

Since a Java upgrade to openjdk version “1.8.0_302”, everything is too small to read.

By “everything” I mean all text on menus, all values, and text in a GPX file that I’ve loaded in JOSM. How do I make everything bigger?

Edit: The problem turned out to be entirely unrelated to JOSM in the end.


I had the same problem suddenly moving to a 4K monitor, but I’m using openSUSE OS.

In Linux you can easily scale that.
You start JOSM with a special command:

“export GDK_SCALE=* && josm”

(* is a number, such as “2” or “3”)

You can enter this in the console or you can create a small script.

I’m sorry I can’t help you there in Windows, but I hope, there is a similar solution.


While that wasn’t the answer for Windows, it did point me in the direction of the answer, so thanks for that. Scaling on Windows is handled by Windows 10 compatibility settings, as described at

Locating Java via “where java.exe” found both “C:\Program Files\OpenJDK\jdk-18\bin\java.exe” in the path (which I was expecting) and “C:\Program Files\Eclipse Foundation\jdk-8.0.302.8-hotspot\bin\java.exe” which I wasn’t. recently upgraded the OpenJDK from jdk-17 to jdk-18; and at the same time this seems to have dropped behind the “unexpected” old JDK in the path. Testing with each showed that the old Java had the scaling issue but OpenJDK 18 did not, so I could just uninstall JDK 8 to fix the problem.

Had that not worked the Windows 10 compatibility settings described in the SuperUser article would presumably have worked, as would “explicitly saying which Java to run” and changing the path around so that JDK 8 was after JDK 18.


I had a scaling issue when the installer switched. There was some discussions about it on the JOSM bug tracker: #21278 (JOSM.exe runs upscaled) – JOSM

I had to tell Windows to put all of the scaling responsibility on the application and it matched the rest of the system after that.


You can also have a look at the myHDPI mapcss stylesheet that can be added to JOSM.

I’ve tuned it to my taste.

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