UTM parameters FAQ

UTM parameters are tags you add to the end of a URL to tell your analytics tool where a visitor came from. They were created by Urchin (the “U” and “T” in UTM) and became standard after Google acquired Urchin and built it into what is now Google Analytics. Try the builder if you want to see one in action.

utm_source (the platform — e.g. google, newsletter), utm_medium (the channel type — e.g. cpc, email, social), utm_campaign (your campaign name), utm_id (a unique campaign ID, often an ad platform macro), utm_term (paid keyword or ad set), and utm_content (the specific creative or link variant).

utm_source, utm_medium, and utm_campaign. These are the “original three” that every analytics tool supports out of the box, and together they answer the three questions every marketing report asks: where did this traffic come from, what channel type was it, and which specific campaign drove it? If you only have time to fill in three, fill in these.

utm_source identifies the specific platform (google, facebook, newsletter). utm_medium identifies the category of marketing channel (cpc, email, social, referral). Think of it as: source answers “which site sent this visitor” and medium answers “what kind of traffic is this”. Both should use lowercase, consistent values.

GA4 uses utm_id as the primary join key between your ad-platform cost data and your site behavior. When you fill utm_id with a platform macro like {campaignid} (Google Ads) or {{campaign.id}} (Meta), the real campaign ID flows through at click time and GA4 automatically reconciles costs, clicks, and conversions. Leaving utm_id blank forces GA4 to fall back to fragile name-based joins. Full explainer.

Because roughly 99% of marketing platforms — Google Analytics, Mixpanel, Amplitude, HubSpot, Segment, every ad platform — recognize and report the six standard utm_* keys out of the box. Using a non-standard key means the data is captured in the URL but invisible in your reports unless you configure custom dimensions. Sticking to the standards keeps your data portable across tools and teams.

Yes. UTM values are case-sensitive in every major analytics tool. Google, google, and GOOGLE are treated as three different sources and will split your reports. Pick lowercase and enforce it as a team convention. See best practices for more rules.

Use hyphens. Spaces have to be URL-encoded as %20 and look ugly in analytics reports. Underscores work but GA4 and some tools treat them as token separators. Hyphens are the portable, readable default: spring-sale-2026, not spring_sale_2026 or spring sale 2026.

No — this is one of the most common and damaging UTM mistakes. Internal links with UTM parameters overwrite the visitor's original traffic source in your analytics, so a visitor who arrived from Google Ads gets re-attributed to your internal link the moment they click anywhere on your site. UTM parameters belong on external traffic only: ads, emails, partner links, social posts. This story includes a real-world example of how this breaks reports.

No. Google Analytics reserves the utm_ prefix for its known five parameters (source, medium, campaign, term, content) plus utm_id. Custom keys like utm_brand, utm_product, or utm_region are typically ignored or rejected by GA4 and treated inconsistently by other platforms. If you need a custom dimension, use a non-utm_ key name like brand_name, product_id, or region.

No — this is probably the most misunderstood part of UTM tracking. GA4 only reports the six standard utm_* parameters out of the box. Any custom parameter you add to the URL (ref=, brand_name=, tblcid=, etc.) is captured in the page_location hit but will not appear in any report until you explicitly create a custom dimension in GA4 and map the query parameter to it. Without the custom dimension, your extra data is effectively invisible.

Not directly, but they can cause duplicate-content issues if search engines index versions of your URL with different UTM values. Set a <link rel="canonical"> tag pointing to the UTM-free version of each page, and keep UTM parameters out of internal links on your own site. Use them only on external traffic (ads, emails, partners).

Yes — as long as the custom key does not start with utm_. Your analytics tool will happily accept extra query parameters for platform click IDs (tblcid, ob_click_id, rdt_cid) or partner tracking (ref=partner-x). Just remember that custom parameters need a custom dimension in GA4 to actually appear in reports. The builder lets you add any key/value alongside the standard UTMs.

Paste the full tracked URL into a browser, load the page, then check your real-time analytics report. You should see the visit attributed to the source and medium you set. For ad platforms with dynamic macros, use the platform's “preview” or “test click” tool to see the macro substituted with a real value before the campaign goes live.

Use both. Platform click IDs (gclid from Google, fbclid from Meta, msclkid from Microsoft, ttclid from TikTok) handle attribution back to the ad platform's own reporting. UTM parameters handle attribution in your analytics tool, your CRM, and cross-platform reporting. They don't conflict — they serve different systems and both should be in place.