How can you permanently zoom in Firefox without using an add-on?

Does Firefox have a zoom option similar to Internet Explorer, Chrome & Opera's zoom to x% option?


Notice: These settings may not work with version 29 or newer.

Open Firefox and type about:config into the address bar and search for "zoom".

In the search results, change two settings as below.

browser.zoom.siteSpecific false
zoom.minPercent 150

The value of zoom.minPercent must be an integer.

  • Emperically determined: Firefox must be restarted before it takes effect, at least for zoom.minPercent. Tested with Firefox 8.0.1 (Portable edition) – Peter Mortensen Feb 15 '12 at 9:40
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    This does not work with Firefox 29 – Steven Penny May 4 '14 at 7:58
  • I guess this is a bug in 29. I did the changes and restart the firefox. All sites started in %100. When I touch ctrl+scroll, page became %150 zoomed. I think, somehow, they broke zoom.minPercent behaviour option on startup. – Sencer H. May 5 '14 at 9:03
  • Version 47 and still this method doesn't work – D.Snap Aug 3 '16 at 8:50
  • Or one can simple set zoom.minPercent 150 and zoom.minPercent 150. – mk1024 Jul 5 '19 at 21:02

From https://superuser.com/a/1268867 :

The default zoom in Firefox can be reset to any value for all webpages without installing an extension.

  1. In the Firefox address bar type: about:config

  2. Search for this preference: layout.css.devPixelsPerPx

  3. Replace the default value of -1.0 with the new percentage zoom. For example, if you want to change the default zoom from the default value of 100% to 125%, then change the value of layout.css.devPixelsPerPx to 1.25

This affects the GUI and web content, not just the web content or just the text.


Not sure if this is what you ask for, but you can increase the minimum font size on you browser. That way you'll have larger letters.

like this: increase-min-fint-size

  • 1
    not just the font size .... the whole webpage – Niks Jan 4 '12 at 13:33
  • scroll up the page - you might find your answer. – karla Jan 4 '12 at 13:33
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    that isn't permanent zoom – Niks Jan 4 '12 at 13:35
  • I made a little search - there seems not to be such an option. But wikipedia's acticle about firefox says, that it should remember your zooming settings for each site. – karla Jan 4 '12 at 13:40

Control+MouseWheel zooms, and the zoom-level is remembered on a per-site basis, unless you clear your history.

  • 1
    (ctrl and + ) (ctrl and -) browser/tab wide zoom = same like ctrl mouse wheel up/down – Piotr Kula Jan 4 '12 at 13:36

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