UTM parameters explained: what they are, how to build them, and how to confirm they work

A UTM parameter is a name-and-value tag appended to a link after a question mark. On its own, a link like example.com/sale tells your analytics nothing about how the visitor arrived. Add UTM tags — example.com/sale?utm_source=newsletter&utm_medium=email&utm_campaign=spring-sale — and the same visit is now labelled by source, channel, and campaign.

UTM stands for Urchin Tracking Module. The convention comes from Urchin, an early web-analytics product Google acquired and turned into Google Analytics, and it has been the standard way to tag campaign links ever since. Every major analytics platform — GA4, Adobe, Matomo, Piwik — reads the same utm_ tags, which is why UTMs are portable across tools.

The tags do not change the page the visitor sees; they only carry information for your analytics. That is the whole point: a tagged link behaves exactly like the untagged one for the visitor, while giving you the attribution you would otherwise lose.

There are five UTM parameters. Three are effectively required if you want clean reporting, and two are optional and mostly used for ads and A/B tests.

Fill in at least source, medium, and campaign on every tagged link. Leaving one out is the single most common reason campaign reports look inconsistent.

The structure is your normal page URL, then a question mark, then each utm_ tag joined by an ampersand. Order does not matter; spelling and casing do. A complete example: example.com/pricing?utm_source=newsletter&utm_medium=email&utm_campaign=spring-sale&utm_content=header-cta.

The safest habit is a naming convention you apply every time. Keep everything lowercase, because UTM values are case-sensitive: Facebook, facebook, and FaceBook become three separate sources in your reports. Use hyphens or underscores instead of spaces, never raw spaces. Keep a shared list of the exact source and medium values your team is allowed to use, so one person does not write “email” while another writes “e-mail.”

You can assemble links by hand once you know the pattern, or use a URL builder that fills in the fields and encodes the result for you. Either way, the rule that matters is consistency: the same channel must always be tagged the same way, or your reports will split one channel into several.

Most UTM problems are not dramatic — they do not throw an error. They just fragment or misattribute your data until the reports stop being trustworthy.

Watch for these in particular:

Once a tagged link is clicked, GA4 reads the tags and stores them against the session. In GA4, open Reports, then Acquisition, then Traffic acquisition, and look at the “Session source / medium” dimension — your utm_source and utm_medium appear there. To see campaigns, add or switch to the “Session campaign” dimension, which shows your utm_campaign values.

If you tagged a link and the values never appear, the usual causes are a redirect that stripped the query string, a typo in a utm_ key (utm_soure instead of utm_source is ignored), or the visit being attributed elsewhere because the link was an internal one you should not have tagged.

If your UTM values are missing entirely and you are not sure whether GA4 is even receiving hits, the problem may be upstream of UTMs — the GA4 tag itself may not be firing on the page.

UTMs decide how a visit is labelled, but they cannot record anything on their own. They rely on your analytics and pixel tags actually loading and firing on the page. A perfectly tagged link pointed at a page where the GA4 tag or the Meta Pixel does not load will still produce no data — the label had nowhere to be recorded.

So UTM hygiene and tag health are two separate checks, and you need both. Get the tags consistent, then confirm the analytics and pixel tags are genuinely present and firing on the pages your campaigns send traffic to. TrackCanary’s free checkers run that visible check across your public pages, so you know a campaign click is actually being recorded — not just labelled.