UTM source (utm_source) is a tracking parameter that identifies the specific website, platform, or publication that sent a visitor to your site. It answers the fundamental question: “Where did this traffic come from?”—whether it’s a social network like Facebook, a search engine like Google, or a specific newsletter .
TL;DR
- utm_source is one of the five UTM parameters and is required alongside utm_medium and utm_campaign for effective tracking .
- It identifies the exact origin of your traffic—the specific platform, website, or referrer where the link appeared .
- Common values include facebook, google, newsletter, and instagram .
- Case sensitivity matters—Facebook and facebook will appear as separate sources in your reports. Always use lowercase for consistency .
- While the source is the specific origin, the medium is the broader channel category (e.g., if source is facebook, medium would be social) .
What Problem Does utm_source Solve?
Imagine you share the same landing page link on your Facebook page, in a newsletter, and through a Google ad. Without tracking, your analytics would show visits to that page but wouldn’t tell you which channel actually sent them .
utm_source solves this by letting you create unique versions of the same URL for each placement. When someone clicks, the parameter travels with the request and your analytics tool records the source, showing you exactly where each visitor came from.
utm_source vs. utm_medium: Understanding the Difference
The key distinction between source and medium is specificity. Source is the specific origin platform, while medium is the broader channel category .
| Parameter | Question It Answers | Example Values |
|---|---|---|
| utm_source | Where did the traffic come from? (specific platform) | facebook, google, monthly_newsletter |
| utm_medium | How did the traffic arrive? (broad channel) | social, cpc, email |
For example, if your source is facebook, the medium would typically be social. If your source is a monthly_newsletter, the medium would be email .
Common utm_source Values and Their Use Cases
Choosing clear, consistent source names is essential for clean data. Here are common values and when to use them:
- google – For traffic from Google search, including both organic and paid results. Paired with organic or cpc as the medium.
- facebook – For traffic from any Facebook placement, whether a post, ad, or page link .
- instagram – For traffic from Instagram posts, stories, or ads.
- newsletter or monthly_newsletter – For traffic from email marketing campaigns .
- linkedin – For traffic from LinkedIn posts or advertisements.
- email-signature – For links placed in your email signature block .
- bing – For traffic from Microsoft’s Bing search engine.
Best Practices for Using utm_source
Use lowercase consistently. UTM parameters are case-sensitive, so Facebook and facebook will be treated as entirely different sources in your analytics reports .
Be specific but not overly long. google_ads_retargeting is more descriptive than google, but avoid unwieldy values like google_ads_retargeting_campaign_april_2025.
Use underscores for spaces. Use email_signature rather than email signature to prevent browser encoding issues .
Match source values to specific placements. If you share the same URL in two different Facebook groups, use distinct source values like facebook_group_a and facebook_group_b to see which performs better.
Consider using a UTM builder tool. These tools ensure you format values correctly and include all required parameters .
How utm_source Data Appears in Analytics
When you’ve deployed tagged links, the utm_source values appear in your analytics platform under the “Source” dimension. In Google Analytics, you can view this data in Reports > Acquisition > Traffic acquisition .
You’ll see sources grouped alongside mediums and campaigns, allowing you to answer questions like:
- Which social platform drives the most engaged traffic?
- Do newsletter visitors convert better than search visitors?
- How does traffic from facebook_ads compare to facebook_organic?
Frequently Asked Questions
Is utm_source required?
Yes. Together with utm_medium and utm_campaign, utm_source is one of the three required parameters for proper campaign tracking .
What happens if I don’t use utm_source?
Without utm_source, traffic from your campaigns will likely be categorized as “direct” or “(not set)” in your analytics, making it impossible to identify which specific placements are driving visitors .
Is utm_source case-sensitive?
Yes. Facebook and facebook will appear as separate sources in your reports. Always use lowercase for consistency .
What should I use as my source value?
Use the name of the specific platform, website, or publication where the link appeared. For example, google, facebook, newsletter, or linkedin .
Sources
- Bitly Support: What are UTM parameters?
- Marfeel: UTM parameters for custom traffic attribution
- Talon.One: Importance of UTM in marketing
- GoSquared: Source
- Google Analytics Blog: Getting Started with Analytics Measurement
Have a specific UTM tracking challenge? Share your question in the comments below.
