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Glossary Term

utm_source

glossary utm source featured

utm_source is the UTM parameter that identifies the specific platform, website, or publication that sent a visitor to your site. It is one of the three required UTM parameters in Google Analytics 4, alongside utm_medium and utm_campaign. The value gets stored in GA4’s “Session source” dimension and feeds the traffic acquisition reports that show which sources drive visits, conversions, and revenue.

A tagged URL with utm_source looks like this:

https://example.com/?utm_source=facebook&utm_medium=social&utm_campaign=spring_sale

In this example, facebook is the utm_source value. GA4 records the session as originating from Facebook regardless of how the user arrived.

Why utm_source Matters

utm_source is the first column in nearly every campaign report. Without it, GA4 cannot tell whether a click came from a newsletter, an Instagram ad, or a partner site. All untagged or improperly tagged sessions fall into “(direct)” or “(not set)”, which corrupts attribution data and hides the actual source of conversions.

utm_source also drives GA4’s Default Channel Grouping when paired with utm_medium. The combination utm_source=google and utm_medium=cpc automatically categorizes traffic as Paid Search. utm_source=newsletter with utm_medium=email categorizes as Email.

Common utm_source Values

Standard utm_source values describe the platform or publisher by name. The goal is specificity: name the exact source, not the channel category (the channel goes in utm_medium).

Search engines:

  • google
  • bing
  • duckduckgo
  • yahoo

Social platforms:

  • facebook
  • instagram
  • twitter or x
  • linkedin
  • tiktok
  • youtube
  • pinterest
  • reddit

Email tools and lists:

  • newsletter
  • mailchimp
  • klaviyo
  • hubspot

Partners, publishers, and referrers:

  • partner-name (e. g., producthunt, g2)
  • Publisher domain (e. g., nytimes, techcrunch)
  • Affiliate ID or affiliate network name

Offline and direct channels:

  • qr-code
  • print-ad
  • podcast-name

Use a consistent value for the same source across every campaign. facebook should always be facebook, never Facebook, FB, or fb-ads (the platform name belongs in source; the ad format belongs in utm_medium or utm_content).

utm_source vs utm_medium

The two parameters answer different questions. Mixing them is the most common UTM mistake.

Parameter Question it answers Example values
utm_source Where exactly did the click come from? google, facebook, newsletter
utm_medium What type of channel is that? cpc, social, email, referral

A Facebook ad click should be tagged utm_source=facebook&utm_medium=cpc. A Facebook organic post should be utm_source=facebook&utm_medium=social. The source is identical, the medium is what changes.

utm_source Best Practices

  • Lowercase only. GA4 is case sensitive. Google and google appear as two different sources, splitting traffic across two rows.
  • No spaces. Replace spaces with hyphens or underscores. product-hunt, not product hunt.
  • Name the platform, not the channel. facebook is a source. social is a medium. Keeping them separate prevents data confusion.
  • Stay consistent across campaigns. Decide once whether the value is linkedin or linkedin-ads and stick to it.
  • Avoid generic values. web, website, internet, and direct carry no useful meaning. Name the actual platform.
  • Document approved values. A shared list prevents teammates from inventing new variants like fb, meta, or facebook-business.

linkutm’s UTM naming convention checker flags casing and formatting errors in utm_source values before tagged links go live.

Frequently Asked Questions

What does utm_source mean?

utm_source identifies the specific source of website traffic, such as google, facebook, or newsletter. It tells Google Analytics 4 which platform or publication a visitor came from. Together with utm_medium and utm_campaign, it forms the core of GA4 campaign attribution.

What are common utm_source values?

The most common values are platform names: google, bing, facebook, instagram, linkedin, twitter, youtube, tiktok, pinterest, newsletter, and specific partner or publisher names. Use lowercase and stay consistent across campaigns. Avoid generic values like website or internet.

Is there an official utm_source list?

No. Google does not publish a fixed list of utm_source values. Marketers choose values based on the actual platform sending traffic. The convention is to use the platform’s lowercase name, such as facebook for Facebook or mailchimp for a Mailchimp campaign.

What is the difference between utm_source and utm_medium?

utm_source names the specific platform (facebook, google, newsletter). utm_medium names the channel type (social, cpc, email). A Facebook ad uses utm_source=facebook&utm_medium=cpc. A Facebook organic post uses utm_source=facebook&utm_medium=social. Keeping the two separate prevents attribution errors.

Is utm_source required?

Yes, for any campaign that needs accurate attribution in GA4. Without utm_source, GA4 cannot assign the session to a named source and the traffic falls into “(direct)” or “(not set)”. The other two required parameters are utm_medium and utm_campaign.

To build properly tagged campaign links with consistent utm_source values, use the free UTM builder at linkutm.

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