To fit more tabs on the tab strip, Firefox shrinks the width of each tab as the tab strip becomes full. However, there is a pre-defined limit (100 pixels) on how narrow each tab can become.
When the tabs can’t be shrunk any further, the tab strip starts scrolling to handle the overflow. On my test 15” laptop, this 100px tab width limit means that only 12 tabs can be opened before they start to disappear off the edges and the tab strip becomes scrollable (scroll arrow at each end of the scroll bar).
Browsing on a netbook/ultrabook with a smaller screen results in even fewer tabs being visible before scrolling begins.
By comparison, Google Chrome can shrink tabs much smaller – this allows more to be displayed in the tab strip without having to scroll. On the same laptop I could display 100 tabs in Chrome’s tab strip without any scrolling. Whilst 100 tabs is probably excessive, 12 may not be enough for keen Firefox users.
How To Keep Tabs Visible in Firefox?
Firefox 3.6 used to include the pre-defined limit as a preference in about:config – ‘browser.tabs.tabminwidth’. Changing the value of that preference from 100 to a lower value (minimum of 36px) would allow the tabs to shrink a lot further and fit more into the tab strip.
Sadly Mozilla removed that preference from Firefox 4 onwards – advanced users can specify the tab width using CSS in UserChrome.css but that is outside the scope of this article. Most users will find it easier to keep tabs visible in Firefox with one of the following add-ons:
Tab Mix Plus (TMP) – hugely popular Firefox addon to enhance tab browsing that includes a host of features. It does the job perfectly but it is a large, and sometimes complex, add-on to use just for this purpose.
To prevent tab overflow using TMP, open its Options and navigate to Display \ Tab \ Tab Width – here you can set the minimum and maximum widths of tabs. The defaults are 100 to 250 pixels.
If you don’t need all its other features, a much simpler and quicker add-on to do this specific job is Prevent Tab Overflow:
Prevent Tab Overflow – gains 5 out of 5 star ratings and does not require restart after installation. It reduces the minimum width of tabs so they can shrink to a smaller size before going into overflow.
Install the add-on and browse to its Options – via Menubar (or Tools) then Add-ons \ Extensions.
The options let you set the tab width – 3 choices are available: 36px, 54px and 72px.
Choose the setting you want – as a guide: the default minimum is 100px so setting it to 36px will allow almost 3 times as many tabs to be displayed before scrolling e.g. on my test laptop it allowed 35 tabs.

Other options include:
Disable tab open/close animations – allows quick tab resizing when too many tabs are open.
Hide blank tab favicons – lets you seeing more of the tab title on narrow tabs.
Hide close button from active tab – OFF by default. Only takes effect whilst not hovering
Slimmer pinned tabs – may be very useful if you have lots of pinned tabs.