UTM parameters (Urchin Tracking Module) are tags added to a URL that allow Google Analytics to know where a visitor comes from. Essential for measuring the effectiveness of each marketing channel, campaign and content, they transform anonymous visits into actionable data.
A complete UTM link contains 5 parameters: utm_source (traffic source: newsletter, facebook, google), utm_medium (channel type: email, cpc, social, banner), utm_campaign (campaign name: christmas-promo-2025), utm_term (keyword for paid campaigns) and utm_content (content variant for A/B testing). Only the first 3 are mandatory. UTM parameters are case-sensitive: 'Newsletter' and 'newsletter' will create two different sources in GA.
📐 Formula
Tracked URL = Base URL + ?utm_source=X&utm_medium=Y&utm_campaign=Z
📊 Reference table
| UTM parameter | Required | Typical values | Example |
|---|---|---|---|
| utm_source | Yes | google, facebook, newsletter | utm_source=newsletter |
| utm_medium | Yes | cpc, email, social, organic | utm_medium=email |
| utm_campaign | Yes | campaign-name, summer-sale | utm_campaign=summer-sale-2025 |
| utm_term | No | paid keyword | utm_term=trail+shoes |
| utm_content | No | A/B variant, button name | utm_content=header-button |
💡 Practical examples
Example 1: link for an email campaign
https://mysite.com/promo?utm_source=newsletter&utm_medium=email&utm_campaign=summer-sale-2025&utm_content=cta-button — In GA4, this traffic appears under Source/Medium: newsletter/email, Campaign: summer-sale-2025.
Example 2: link for an Instagram post
https://mysite.com?utm_source=instagram&utm_medium=social&utm_campaign=product-launch&utm_content=story-post — Distinguishes Stories traffic from regular posts vs bio link.
Example 3: UTM best practices
Always use lowercase. Use hyphens (-) rather than underscores or spaces. Create a shared reference table across your team to avoid inconsistencies (summer-2025 vs Summer_2025 vs summer 2025).