You ran a newsletter campaign and traffic went up — but was it the newsletter, the social posts, or luck? Without UTM parameters, your analytics cannot tell you. UTMs are small tags added to the end of a URL that tell Google Analytics exactly where each visitor came from.
The five parameters
- utm_source — where the traffic comes from: newsletter, google, facebook, partner-site.
- utm_medium — the channel type: email, cpc, social, referral, qr.
- utm_campaign — the campaign name: spring-sale-2026, product-launch.
- utm_term — (optional) the paid keyword, mostly for search ads.
- utm_content — (optional) which variant: header-button vs footer-link, image-a vs image-b.
https://example.com/sale?utm_source=newsletter&utm_medium=email&utm_campaign=spring-sale-2026&utm_content=header-button
How GA4 uses them
GA4 reads UTMs automatically — no configuration needed. Source and medium appear in the Traffic acquisition report, and campaign names get their own dimension. Consistent tagging is what makes the reports meaningful: if one email says utm_source=newsletter and the next says utm_source=Newsletter, GA4 counts them as two different sources.
Naming conventions that keep reports clean
- Always lowercase — GA4 is case-sensitive, so "Email" and "email" split your data.
- Use hyphens, not spaces — spaces become %20 and are easy to mangle.
- Agree on a small fixed vocabulary for medium (email, social, cpc, referral) and never improvise.
- Put dates or versions in utm_campaign, not in source or medium.
Build them without typos
Most broken campaign tracking comes from hand-typed URLs: a missing ?, a duplicated &, an uppercase source. A UTM builder assembles the link for you from labelled fields, encodes special characters correctly, and lets you copy a clean, ready-to-paste URL. Tag every external link consistently for a month, and your acquisition reports go from guesswork to an actual map of what works.
Where UTM falls short — and what fills the gap
UTM only tells you which link was clicked; it cannot join a click to a purchase unless your analytics tool links the session. It also distinguishes clicks, not people: two visits from the same campaign are two sessions. Paid platforms add their own click IDs (GCLID, FBclid) that encode ad-level data — mobile-app and server-side event data does the actual attribution. Use UTM to run clean manual campaigns; trust the platform click IDs for ad management.
- Case matters: “Email”, “email” and “EMAIL” are three different utm_campaign values.
- Autofill utm_id when you need to map a code back to an ad system.
- Strictly URL-encode values with spaces — many tools paste raw values and corrupt the link.
