This page will show you how to use the command line to start Firefox with a specific window size.

The following command is an example of, how to start Firefox with a specific window size of 1200×1200 and open the homepage of Firefox. This is a fine size for screenshots.

 $ firefox -width 1200 -height 1000 https://www.mozilla.org/en-US/firefox
Picture of Firefox with specific window size of 1200x1000.
Picture of Firefox with specific window size of 1200×1000.

Published by Micski

Micski lives in Copenhagen, which is the capitol city of Denmark, where he's a system administrator of information technology and a semi-professional poker player.