GA Campaign Tracking Parameters: What's Really Required?

September 03, 2009
Senior Director of Data Platforms

Google Analytics campaign tracking is great, and we’ve talked about it lots before. The official story with the campaign tracking parameters is that Campaign, Source, and Medium (utm_campaign, utm_source, utm_medium) are all required. It says so in the the URL builder tool, for example.

I wondered though, what would happen if you left one or two of these off? Would campaign tracking still work?

The short answer is: As long as you include a source (utm_source), campaign parameters still work.

If the URL has the utm_source parameter, cookies get set correctly. If it has one of the other parameters but no utm_source, the cookies about where a visitor came from don’t get re-set at all (similar to using utm_nooverride=1).

What does it look like in reports? If you leave off either utm_medium or utm_campaign, you just get “(not set)” as the value for those fields (shown here in the All Traffic Sources and Campaign reports):

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Although I still recommend using all three fields for campaign tracking, this does have one take-home lesson: If you have situations in which URLs might get cut off (such as a plain-text email), always put the source first. This will help ensure you’ll at least get some data even if the other parameters are lopped off.