I know this is going to seem like a strange question, but are their any stats on users narrowing their browser window so that media queries kick in and display the mobile optimised version of the site?

We're about to mobile optimise our website. As we haven't done this we cant use our analytics to answer this question.

  • What is your concern here? Or are you asking this out of random curiosity? Commented Mar 14, 2012 at 0:55

3 Answers 3


Resizing during a session, or actual browser window size vs screen size?

It's impractical (See @JacobHume's comment below) to tell if a user is changing the window size while browsing but Chris Coyier over at CSS Tricks has come up with a way to track the window size onLoad, (results below) and zachstronaut has a similar method using Google Analytics.

Chris's article is really very enlightening, even if it is based on a small sample of CSS Tricks users. The broad conclusion is that 61% of users have their browser window within 200px of their screen size, only 1% have it fully expanded.

You could implement either script and get a fast view of the actual screen sizes your users have in a few hours, which if not conclusive, would give you a better idea than no data at all.

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Should I track screen size

To add at little more detail to my reply to @JacobHume's comment below. IMHO There are practical limits in terms of volume of data gathered, impact on front end efficiency, business need and the behavioral meaning of the data when tracking window size.

Tracking every single window resize event could provide dozens of resize events per user, you could only track the start and endpoints, but the real questions are:-

  • Will that screen size data tell you anything useful about your users needs?
  • Will my users buy more things/see more ads/read more stuff if I support different screen sizes?

Ultimately in an increasingly fragmented mobile/micro-tablet/tablet/tv/oh-my-god-what-do-you-mean 'internet fridge'?! space all you actually need to know is that you have enough users with widely differing screen resolutions to justify (from a business perspective) moving to a responsive design.

You may then need to ask (if you can't justify the development effort to go fully scaleable) which screen resolutions you should focus your design/development time on.

Everything else is interesting but academic. The real point is that you can easily answer all but one of these questions from your existing screen resolution data.

  • I don't think "impossible" is accurate: would not window.onresize (developer.mozilla.org/en/DOM/window.onresize) give you a way to track this?
    – Jacob Hume
    Commented Mar 13, 2012 at 20:15
  • @JacobHume you make a fair point, I did look at an implementation of that but the results are unhelpful and distorting (too much data) + its quite heavy duty on the front end so detracts from the experience. I should change the answer to impractical. Commented Mar 13, 2012 at 20:31
  • 1
    Agreed - I've been looking around, and haven't found a very reliable way to track it just yet. If I can figure it out, I'll post it - but so far I think your answer covers it very well. :)
    – Jacob Hume
    Commented Mar 13, 2012 at 21:20
  • @JacobHume thanks Jacob. I expanded the answer a bit to cover 'should I track this data' in more depth. Commented Mar 13, 2012 at 21:39

Here are a few applications that let you test your websites mobile version


Is that what you meant about narrowing windows on a desktop to see a mobile version for development and testing reasons? If so there's some good apps in the link above for that.

I also think narrowing a browser wont kicking a mobile version since the user agent is not from a phone


The http://www.responsinator.com/?url=about:blank website is great for testing on multiple devices.

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