Tweak Firefox 3 full page zoom

Firefox 3 introduces full page zoom, that is, instead of just making text bigger or smaller, it resizes the full page including images and layout.

1. If you just want to zoom text, in the View menu, select Zoom and mark Zoom Text Only.

2. Firefox 3 remembers what zoom level you used for viewing pages in a domain and will automatically zoom them the next time you visit any page in the same domain. If you prefer Firefox not to remember it:

  • In the location bar, enter about:config to access the advanced preferences
  • Look for browser.zoom.siteSpecific and double click it to set it to false.

3. Another change you may quickly notice is that in Firefox 3 pressing Ctrl (or Cmd on Mac) and scrolling up and down, zooms the page in and out, unlike Firefox 2 and previous versions which used to work the opposite way.

4. By default when you press Ctrl + = and Ctrl + - to zoom in or out a page (Cmd + = on Mac), Firefox magnifies to 30%, 50%, 67%, 80%, 90%, 100%, 110%, 120%, 133%, 150%, 170%, 200%, 240% and 300%. If you want to define more or less fine steps or need to zoom to larger levels you can customize Firefox full page zoom:

  • Enter about:config in the location bar to access the advanced preferences.
  • Look for toolkit.zoomManager.zoomValues and replace the default values with your preferences. For example to set quicker values like 10%, 50%, 100%, 200%, 300% and 500% you will need to enter .1,.5,1,2,3,5.
  • You will also need to increase the default 300% zoom in level. Look for zoom.maxPercent and set it to 500 to match the highest step set above.
  • You may need to to do the same with the lower limit. Look for zoom.minPercent and set it to 10 to match the lowest step set above.

Note that the zoom steps only affect zooming in and out with the keyboard or via View>Zoom>Zoom In/Zoom Out. Mouse scroll zooming uses its own steps but respects the maximum and minum zoom levels.

Also there seems to be no limit to the zoom level. I was able to set a 5000% cap and get a ridiculously large page.

9 Comments

  1. antistress June 19, 2008 6:06 pm 

    there are privacy concerns about that : if i’ve already visited a site and i’ve adjusted the zoom factor, next time someone else go to that site i’ll see that zoom factor has been modfied and therefore that the site has already been visited.
    You can’t delete that information whereas you can delete history etc

    • Pocket September 10, 2008 1:44 pm 

      You can simply hit ctrl 0 and it will flip back to the default view.

  2. Simon June 20, 2008 7:08 am 

    You may need to to do the same…

    You may need to to to to to (fix please) < I don’t mind if this comment will be deleted after you fix this typo :)

    I love your site!
    Percy FTW!

  3. steveballmer June 23, 2008 8:50 am 

    IE does this automaticallY!

  4. Customize Firefox 3 Zooming | ATMac August 13, 2008 1:16 am 

    [...] finally discovered a solution to this dilemma! The Mozilla Links magazine has an article on how to tweak Firefox 3 full page zoom and I was able to use their technique to change the maximum keyboard zooming level to 30 times [...]

  5. Rob Yearicks January 6, 2010 1:41 pm 

    I’m looking for a way to reset the default zoom on my FF3. By that I mean, instead of me having to constantly ctrl+wheel to zoom in pages (I have a large, hi-def monitor, everything is small), set it so that it automatically zooms everything to a set level. Can it be done???

    Thanks.

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