Force IE compatibility mode off using tags

There is the "edge" mode.

<html>
   <head>
      <meta http-equiv="X-UA-Compatible" content="IE=edge" />
      <title>My Web Page</title>
   </head>
   <body>
      <p>Content goes here.</p>
   </body>
</html>

From the linked MSDN page:

Edge mode tells Windows Internet Explorer to display content in the highest mode available, which actually breaks the “lock-in” paradigm. With Internet Explorer 8, this is equivalent to IE8 mode. If a (hypothetical) future release of Internet Explorer supported a higher compatibility mode, pages set to Edge mode would appear in the highest mode supported by that version; however, those same pages would still appear in IE8 mode when viewed with Internet Explorer 8.

However, "edge" mode is not encouraged in production use:

It is recommended that Web developers restrict their use of Edge mode to test pages and other non-production uses because of the possible unexpected results of rendering page content in future versions of Windows Internet Explorer.

I honestly don't entirely understand why. But according to this, the best way to go at the moment is using IE=8.


After many hours troubleshooting this stuff... Here are some quick highlights that helped us from the X-UA-Compatible docs: http://msdn.microsoft.com/en-us/library/cc288325(VS.85).aspx#ctl00_contentContainer_ctl16

Using <meta http-equiv="X-UA-Compatible" content=" _______ " />

  • The Standard User Agent modes (the non-emulate ones) ignore <!DOCTYPE> directives in your page and render based on the standards supported by that version of IE (e.g., IE=8 will better obey table border spacing and some pseudo selectors than IE=7).

  • Whereas, the Emulate modes tell IE to follow any <!DOCTYPE> directives in your page, rendering standards mode based the version you choose and quirks mode based on IE=5

  • Possible values for the content attribute are:

    content="IE=5"

    content="IE=7"

    content="IE=EmulateIE7"

    content="IE=8"

    content="IE=EmulateIE8"

    content="IE=9"

    content="IE=EmulateIE9"

    content="IE=edge"


If you're working with a page in the Intranet Zone, you may find that IE9 no matter what you do, is going into IE7 Compat mode.

This is due to the setting within IE Compatibility settings which says that all Intranet sites should run in compatibility mode. You can untick this via a group policy (or just plain unticking it in IE), or you can set the following:

<meta http-equiv="X-UA-Compatible" content="IE=Edge" />

This works (as detailed in other answers), but may not initially appear so: it needs to come before the stylesheets are declared. If you don't, it is ignored.