How does utm_medium work?
While utm_source tells you where traffic originates, utm_medium tells you how it arrived. For instance, traffic from Google could come via paid search (utm_medium=cpc), organic results, or a display ad — the medium distinguishes between these.
Common utm_medium values
- cpc — paid search (Google Ads, Bing Ads)
- email — email marketing campaigns
- social — organic social media posts
- paid_social — paid social media ads
- referral — links from other websites
- display — banner or display advertising
- affiliate — affiliate partner traffic
Consistency matters — using "email" in one campaign and "Email" in another creates separate entries in your analytics. Define a naming convention and stick with it.
How is utm_medium different from other UTM parameters?
Each UTM tag captures a different dimension of your campaign:
- utm_source — the platform or site (e.g., google, facebook)
- utm_campaign — the campaign name or promotion
- utm_term — the paid keyword that triggered the ad
- utm_content — distinguishes ad creatives or link variants
- utm_id — a unique ID for campaign data import
Think of it this way: utm_source is the who, utm_medium is the how, and utm_campaign is the what.
utm_medium and TTFB considerations
Since utm_medium is almost always used alongside utm_source and utm_campaign, URLs with UTM parameters tend to have high variation. If your caching layer (WordPress, Cloudflare, or another CDN) uses the full URL as the cache key, every unique UTM combination generates a cache miss — degrading TTFB for campaign visitors specifically.
Test your site's performance with utm_medium
Use the tool below to measure how the utm_medium parameter affects your website's TTFB.
