Admin Custom Font plugin allows you to replace default/factory font in WordPress Admin Dashboard with hundreds of different Google Fonts.
Visit Admin Dashboard > Settings > Admin Font to customize font type and styles.
Why This Plugin?
In WordPress version 4.6 a new admin system font change was introduced, moving away from "traditional" Open-Sans font-face type
(introduced back in 3.8). This inspired us to create a simple & powerful Admin Custom Font plugin in order to restore the old look & feel without modifying core files.
Since plugin version 2.4.0 release, you can now choose from the complete list of all Google Fonts, override default font-size and font-weight styles!
Included most popular Google Font types (faces): OpenSans, DroidSans, PT Sans, Roboto, Exo, Play, Lato, Quantico, Orbitron, Maven Pro, fonts designed for specific world languages and more!
In order to streamline and make font selection process more efficient, some 30+ hand-picked, most popular and beautiful Google Fonts are grouped and listed on top of the massive selection list. You should try some of those fonts first, and later explore rest of the available collection.
Read Article:
http://tehnoblog.org/how-to-change-font-in-wordpress-admin-dashboard/