utm.gif Request Parameters Explained


Have you ever wondered how exactly does information about visits to your website get sent back to Google Analytics? Let me introduce you to my good friend, __utm.gif.

GIF Request

You see, whenever a page of your site loads (as long as you have GA tracking code on the page) a request is made for a small file — the __utm.gif. But don’t be fooled by the size of this file (weighing in at only 35 bytes); it packs a lot of information in the request URI of that little pixel. Here’s an example:

Holy parameters, Batman! Let’s break that down now to see what information is being sent back.

utmwv=5.1.7 – Tracking code version
utms=1Session number. Number of sessions/visits from this particular browser Session requests. Updates every time a __utm.gif request is made. Stops incrementing at 500 (max number of GIF requests per session).
utmn=1894752493 – Unique ID generated for each GIF request to prevent caching of the GIF image
utmhn=www.lunametrics.com – Host name, which is a URL-encoded string
utmcs=UTF-8 – Language encoding for the browser. Some browsers don’t set this, in which case it is set to “-”
utmsr=1280×1024 – Screen resolution
utmsc=24-bit – Screen color depth
utmul=en-us – Browser language
utmje=1 – Indicates if browser is Java enabled. 1 is true.
utmfl=10.3 r183 – Flash version
utmdt=Tracking QR Codes with Google Analytics – Page title, which is a URL-encoded string
utmhid=1681965357 – A random number used to link the GA GIF request with AdSense
utmr=http://www.google.com/search?q=tracking+qr+codes&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a – Referral, complete URL
utmp=/blog/2011/08/18/tracking-qr-codes-google-anaytics/ – Page request of the current page
utmac=UA-296882-1 – Account string, appears on all requests
– Cookie values. This request parameter sends all the cookies requested from the page.
utmu=DC~ – This is a new parameter that contains some internal state that helps improve ga.js.

Notice the next to last parameter – utmcc. If you look through that you’ll see all of your cookie information, like visitor ID, how many times they’ve been to your site, how they got to your site, what keyword (if any) they used, etc.

Although that GIF request URI is long, it doesn’t use all the parameters available. Here’s an (almost) full list of the GIF request parameters from Google code. And here are additional eCommerce-specific parameters (scroll down to the bottom) that are nicely summarized.



Thanks to Michael Freeman in his comment below for pointing out a new parameter – utmvp – which indicates the size of the viewing pane. As opposed to utmsr (screen resolution), utmvp is is the actual size of the window pane. For visitors with plugins and toolbars that take up screen space in their browser, you’ll see that utmvp is less than utmsr.

Now it’s your turn

There are a number of free tools that allow you to quickly and easily see what information is being sent in that GIF request (or if it’s even being requested at all). Watch this quick video demonstrating the use of two tools – Firebug and HttpFox (both for Firefox). If you’re a Chrome browser, you may want to try the Google Analytics Tracking Code Debugger. Here’s a list of even more debugging tools.


Jim Gianoglio is a Manager for the Analytics & Insight department. He works with implementation, analysis and training of Google Analytics and Google Tag Manager. Before focusing on analytics, he led the SEO campaigns of Fortune 500 companies in the insurance, retail and CPG industries. Things you didn’t know about Jim: he’s biked from Pittsburgh to Washington DC in 41 hours, roasts coffee beans and has done voiceovers for TV commercials.

  • Hi,

    Thank you for useful post.

    I’m wondering if “utms” is a pageview or event counter.
    I see __utm.gif requests by Fiddler, “utms” increases by tracking pageview.

    I hope I may be sure about utms.


  • Hideki – thank you for the comment! I was a bit too hasty when I stated it was a session number – that is incorrect (I’ve edited the post to reflect that).

    It is actually a counter for session requests. So anytime a __utm.gif request is made (page loads, _trackEvent is triggered, transaction information is sent, etc.) this parameter increases. It stops incrementing at 500 – the max number of GIF requests per session.

    Here’s a thread in the GA help forum with a little more detail – http://www.google.com/support/forum/p/Google%20Analytics/thread?tid=155491dc70c10cab&hl=en

  • rahul

    thanks jim for this post i have have been working on Google analtics from last 2 months and got a lot useful stuffs from lunametrics blog and other resources.
    you indicated a link additional eCommerce-specific parameters is not working,plz help me out with that if you can.

    Another place where i am bit confused is _utmv and _utmz.I want to know what is use of these parameters in GA.

  • Jim,

    Thank you for your reply. Now I may understand correctly about utms.


  • Hi Rahul –

    Welcome to Google Analytics! I’m glad you’re able to find some help on our blog.

    The link to the additional eCommerce-specific parameters should be working (I just checked it).

    __utmv cookies are used for custom variables, and __utmz cookies are used to store traffic sources and navigation information.

    For more information on the utmv and utmz cookies (and all the other cookies that GA sets) I suggest reading through this Google code page – http://code.google.com/apis/analytics/docs/concepts/gaConceptsCookies.html

    It lists out the different cookies that are set by GA along with descriptions of each cookie.

    Hope that helps!

  • Jim,

    Thank you for your reply,now i am pretty much clear about functioning of each cookie.


  • My uncle recommended I might like this web site. He was totally right. This post actually made my day. You cann’t imagine simply how much time I had spent for this info! Many thanks, Alpern

  • not seeing utmb as a cookie value set by utmcc. I know that utmc is no longer in use, but has google also done away with the utmb? if so, what’s taken it’s place?


  • Hi Nate –

    The utmb cookie is just used as a check to see whether the visit is a new or existing session. if the utmb cookie exists, than it’s an existing session. If there is no utmb cookie, than it’s a new session and the session counter portion of the utma cookie (the number at the very end) is updated. For example, if my utma cookie looks like this:


    The number 3 at the end indicates that this is my third visit/session.

    Since the utma value is passed in the utmcc parameter of the gif request, GA doesn’t need to pass the utmb value (it would be redundant).

    It’s also worth noting that although the utmc cookie is no longer being used to calculate sessions, it is still being set by GA (not sure why).

    Hope that helps!

  • You should add to the list the new parameter: utmvp This is the value for Viewing Pane (or the viewable area of the page). For example you’ll now see something like this in the request

    utmsr is the screen resolution, but the utmvp is the actual size of the window pane (in my example I have firebug open on a maximized window which eats up a lot of the height of the screen making the visible area of the window only 291 pixels.

  • @Michael – thanks for adding to this ever growing list! Sometimes it’s hard to keep up with all the additions.

    I added an update to the post with this new(ish) parameter.


  • Dicas WP

    Hi, I think your blog might be having browser compatibility issues.

    When I look at your website in Ie, it looks fine but when opening in
    Internet Explorer, it has some overlapping. I just wanted to give you a quick heads up!
    Other then that, wonderful blog!

  • Thanks for this info. I used parts of it to create a simple/small C# code snippet to submit data to Google Analytics.

    You can the details of what I did in this (long) blog post: http://blog.diniscruz.com/2013/01/creating-server-side-google-analytics.html

  • testing machne of unversal testing machine like impact testing machine izod and brinell testing machine use in engineering colleges foundry industries for check hardness of metal


    Thanks for this info!
    Currently i have a confusion that is there any parameter or way to caculate the load/display duration of a webpage by using _utm.gif?

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