Increasing font size in RStudio

Ctrl++, and Ctrl+-

More keys might be necessary to generate +/- (for instance, for me Zoom In is Ctrl+Shift+=).

Other notes:

• You can also zoom in using the View menu
• See a list of keyboard shortcuts with Alt+Shift+K (recent versions of RStudio only)

Tool --> Global Options --> Appearance --> Then you can adjust the font size at the right panel