UTM Parameters

What Are UTM Parameters?

UTM parameters—short for Urchin Tracking Module—are tags added to the end of a URL to track the source and behavior of incoming traffic in analytics platforms like Google Analytics 4.

These parameters help you answer questions like:

• Where did the visitor come from?
• What campaign or promotion attracted them?
• How did traffic from different sources perform?

UTM-tagged URLs are most commonly used in marketing emails, social media posts, paid ads, and A/B tests. When someone clicks the link, the UTM data is passed to your analytics tool, which logs the visit under the specific source, medium, or campaign you defined.

The 5 Main UTM Tags

A complete UTM string includes up to five parameters:

• `Utm_source`: Where the traffic came from (e.g., Facebook, Newsletter)
• `Utm_medium`: The marketing medium (e.g., email, cpc, social)
• `Utm_campaign`: The campaign name or promotion (e.g., spring_sale)
• `Utm_term`: Paid keywords or targeting terms (mostly for paid search)
• `Utm_content`: Used to differentiate between multiple links (e.g., “heroCTA” vs “footerCTA”)

Each parameter provides a layer of segmentation for your traffic and performance data.

Example of UTM Parameters on a URL

`https://example.com/landing-page?utm_source=newsletter&utm_medium=email&utm_campaign=spring_promo&utm_term=discount&utm_content=cta_button`

Breakdown:

• `utm_source=newsletter` → Traffic is coming from an email newsletter
• `utm_medium=email` → The channel is email
• `utm_campaign=spring_promo` → The campaign is named “spring_promo”
• `utm_term=discount` → Optional; could represent a targeted keyword or offer theme
• `utm_content=cta_button` → Differentiates this link from others in the same email (e.g., button vs. text link)

This tagging allows you to track how well this specific newsletter email drove traffic and conversions to the landing page during the spring promotion campaign.

Why UTM Tracking Matters in A/B Testing

UTM tracking becomes especially useful in experiments when you’re driving traffic from multiple channels or running multiple treatments at once. It allows you to:

• Attribute conversions to specific marketing campaigns or creatives
• Compare how different traffic sources interact with each variation
• Segment test data more precisely by channel, campaign, or content
• Run QA by tagging URLs with identifiers like `utm_medium=qa` to test targeting or variation performance before launch

By layering UTMs into your test URLs, you can evaluate whether, for example, social media traffic prefers version A while email traffic performs better with version B, helping you make more nuanced decisions.

Real-World Examples of UTM Use in A/B Testing

• Social media campaigns driving to different landing page variants tracked with unique `utm_campaign` values
• QA links using `utm_medium=qa` to safely preview A/B test behavior before going live
• Email A/B tests tagged with different `utm_content` values to compare subject line performance by open and click-through rates
• Multi-channel tests where UTM parameters help determine which audience segments engage best with each experiment treatment

“We find that UTM tracking remains an effective method for tracking specific inbound campaign performance across different channels, mediums, and experiments.

UTM tracking is particularly helpful for segmenting data when running experiments, as it allows us to produce stronger, more granular insights that may involve different messaging, promotions, or experiences being served to users.

However, we are mindful of the limitations of UTM tracking in recent years, especially as privacy regulations have become much stricter. Therefore, we favor an agnostic approach to tracking and attribution that includes UTM tracking alongside data modeling techniques and server-side tagging.”

Ginny Forshaw, Co-Founder and CRO Consultant at Convertex Digital

Limitations of UTM Parameters

While powerful, UTM tracking has its drawbacks:

• Easily stripped or overwritten: Some platforms or browsers drop UTM data during redirects.
• Client-side only: UTM data doesn’t persist long unless captured server-side or stored in cookies.
• Privacy regulations: With GDPR, ITP, and other changes, cookie-based attribution linked to UTMs is becoming less reliable.
• Manual effort: Poor UTM hygiene (inconsistent naming, typos) can clutter your analytics.

That’s why more teams are combining UTM tracking with server-side tagging and modeled attribution to get more complete insights.

Best Practices for UTM Parameters in Experiments

To make the most of UTM tracking:

• Use clear and consistent naming conventions (e.g., use utm_source=facebook, not FB or fcbk)
• Always tag outbound links in emails, ads, and social posts driving to experiment pages
• Use `utm_content` to tag specific test variants or creatives
• Avoid PII in URLs—never pass user names or emails as UTM parameters
• Pair UTMs with server-side tracking to preserve data accuracy over time

For QA, tagging with `utm_medium=qa` can help isolate test environments or trigger specific variations for internal testing.