UTM parameters explained

The five standard parameters

Google Analytics recognizes five UTM tags. Three are core — without them, traffic shows up as direct or referral. Two are optional but useful for paid search and creative testing.

Together, these five tags form a contract between every link you publish and the analytics platform that ingests the resulting clicks. Get the contract right and your campaign reports answer business questions cleanly. Get it wrong, even slightly, and the same data becomes a fragmented mess that takes hours to reconcile.

• utm_source — the platform sending the click (e.g. facebook, newsletter, partner_blog).
• utm_medium — the broad channel category (e.g. cpc, email, social, affiliate).
• utm_campaign — your campaign name (e.g. spring_launch, bf2025).
• utm_term — the paid keyword that triggered the ad (paid search only).
• utm_content — the specific creative or link variant (used for A/B tests).

The three rules that prevent 90% of mistakes

Most broken campaign reports trace back to the same handful of issues. Pick a convention and apply it everywhere — including for partners who paste your links into their own systems.

These rules feel pedantic until the first time you have to explain a 30% revenue gap in a board update that's actually a tagging discrepancy. The cost of strictness is a few minutes per link; the cost of laxity is a quarter of misattributed spend.

• Always lowercase. 'Facebook' and 'facebook' become two sources.
• Use underscores, never spaces. Encoded spaces (%20) are ugly and fragile.
• Keep medium values from a closed list — cpc, email, social, organic, referral, affiliate. Free-text mediums fragment your reports.

When to use term vs content

utm_term is for the keyword in paid search. If you're not running search ads, you don't need it. utm_content is for distinguishing variants — a hero image vs a product image, a long headline vs a short one. If you're not testing creative, you don't need it either.

Adding empty or duplicate values to either parameter clutters reports without adding signal. Leave them out when they don't carry information.

A useful test: if you can't write a sentence that explains what utm_content distinguishes, the value is probably noise. Strip it.

How analytics platforms read UTMs

Google Analytics 4 captures UTM parameters automatically on session start and uses them to populate the Traffic acquisition report. Adobe Analytics, Matomo, Plausible, and Mixpanel all read the same five parameters — they're a de facto open standard, not a Google-only convention.

Most platforms also store the parameters as event properties, so you can slice conversions or downstream actions by source, medium, and campaign even months after the visit. That's why getting the values right at the moment of click capture matters so much: you can't retroactively re-tag historical sessions.

Build your URLs without typos

Hand-typing UTMs is where mistakes creep in. Use the UTM Builder to generate validated, properly encoded URLs, then drop them into your ad platform or email tool. For a library of channel-specific patterns, the UTM examples guide has copy-ready templates for Google Ads, Meta, LinkedIn, newsletters, and partner placements.

Summary

Three parameters are non-negotiable, two are situational, and a handful of formatting rules separate clean reporting from a tagging spreadsheet you'll dread. Choose a convention, document it, and use a generator so every URL you publish follows the same shape.