How to Change the Default Languages in Mozilla Firefox

Updated September 30, 2019

Some websites can be rendered in several different languages, depending on their configuration and your web browser's abilities and settings. Firefox, which supports over 240 global dialects, provides the ability to specify which languages you prefer to use when viewing web content.

Before rendering text on a page, Firefox first validates whether or not it supports your preferred languages in the order that you specified them. If possible, the page's verbiage is then displayed in your preferred language. Not all web pages are available in all languages.

How to Specify Preferred Languages in Firefox

Setting and modifying Firefox's list of preferred languages can be done quickly.

Choose Firefox > Preferences from the menu bar to open the Preferences screen.

You can also type about:preferences into the Firefox address bar.
In the General preferences, scroll down to the Language and Appearance section. Click on the Choose button next to Choose your preferred language for displaying pages.
In the Languages dialog box that opens, the browser's current default languages are shown in order of preference. To choose another language, click on the drop-down menu labeled Select a language to add.
Scroll through the alphabetical language list and select the language of your choice. To move it into the active list, click on the Add button.

Your new language should now be added to the list. By default, the new language displays first in order of preference. To change its order, use the Move Up and Move Down buttons accordingly. To remove a specific language from the preferred list, select it and click on the Remove button.

When you are satisfied with your changes, click the OK button to return to Firefox's preferences. Once there, close the tab or enter a URL to continue your browsing session.