This is one of those obvious things that’s not obvious when you need it most. Suppose I’m doing a demo of R for a group like our wonderful Kansas City R Users Group. I want to have a readable sized font. Here’s how you do it.
Go to the menu and select Edit and Gui Preferences. You’ll see this dialog box.
Buried in the middle of everything is a font size. Try a value of 14 or 16 to start. You may need to change the width of your output from the default of 80 to a lower value like 60 or 40. You can do this in the same dialog box (Console columns field) or you can run the function options(width=60) or options(width=40).
If you are cutting and pasting code from notepad into R, then there is an easy way to increase the font size in notepad. Click on FORMAT then FONT and you will see the following dialog box.
Increase the font size to 18 or 24 and everyone will see what you are doing much better.
You can find an earlier version of this page on my blog.