How to enlarge Gimp UI font and icon size for HDPI screen?

Solution 1:

Change icon size

• Preferences
  • Interface
    • Icon Theme
      • Change: guess Icon size from resolution
      • Into: custom Icon Size
      • Drag slider

Change font size

• Close Gimp
• Open the file gtkrc of your specific theme in a text editor
  • Open the Gimp themes directory:
    • Mac: /Applications/GIMP-2.10.app/Contents/Resources/share/gimp/2.0/themes/
    • Windows: C:\Program Files\GIMP 2\share\gimp\themes\
    • Ubuntu: /usr/share/gimp/2.0/themes/
  • Open the gtkrc file for your theme:
    • Light: Light/gtkrc
    • Dark: Dark/gtkrc
    • Gray: Gray/gtkrc
    • System System/gtkrc
    • other
      If you have a customized Gimp, look here for the gtkrc file
      • Mac: ~/Library/Application Support/GIMP/2.10/themes
• Find line with: GimpDock::font-scale = 0.8333
• Replace with: GimpDock::font-scale = 1.6666 (or another value)
• Start Gimp