UTM parameters: a practical guide to tagging campaign links

When someone clicks a link in your newsletter, a social post or a partner's website, your analytics tool tries to work out where they came from. Sometimes it guesses well. Often it cannot tell, and the visit ends up lumped into "direct" or "referral" traffic. UTM parameters fix that by attaching a small label to the link so your analytics can record the source, medium and campaign exactly as you define them.

In this article you will learn:

• what each UTM parameter means and which ones to always use
• how to build a naming convention that keeps reports clean
• worked examples for email, social, paid and offline campaigns
• the mistakes that fragment data or break attribution
• how UTM values appear in Google Analytics 4 (GA4) at the time of writing

What UTM parameters are

UTM parameters are key and value pairs added to the end of a URL after a question mark. For example:

https://example.com/offer/?utm_source=newsletter&utm_medium=email&utm_campaign=spring_sale

When a visitor lands on the page, analytics tools that support UTMs read those values and attribute the visit accordingly. The parameters do not change what the page shows; they only carry information to your analytics.

The parameters and what they mean

Google's Analytics Help documentation lists the following parameters at the time of writing. It advises always using utm_source, utm_medium and utm_campaign whenever you add parameters to a URL.

At the time of writing, Google's documentation notes that utm_creative_format and utm_marketing_tactic are not currently reported in Google Analytics properties. You can include them for other systems, but do not expect to see them in GA4 reports.

In practice, most small teams use five: source, medium, campaign, content and (for paid search) term.

Why consistency matters: values are case sensitive

Google's documentation states that parameter values are case sensitive, so utm_source=google and utm_source=Google are recorded as different values. It recommends a strict naming convention and suggests lowercase as a standard.

If one person tags links with Facebook and another with facebook, your reports show two separate sources, and each looks smaller than the real total. Spaces and inconsistent separators cause the same problem: spring sale, spring-sale and spring_sale are three different campaigns.

Building a naming convention

A convention is a short written rulebook that everyone who creates links follows. It does not need to be complicated. Here is an example you can adapt.

Example convention

• Always lowercase. No capital letters anywhere.
• Use underscores between words. spring_sale, not spring sale or SpringSale.
• Source = the specific site, platform or list. facebook, instagram, linkedin, newsletter, partner_acme.
• Medium = the channel type, from a fixed list. For example: email, social (organic posts), paid_social, cpc (paid search), display, referral, affiliate, qr.
• Campaign = what you are promoting, plus a date if it repeats. spring_sale_2026, webinar_2026_10, product_launch_x.
• Content = which creative or link. hero_button, text_link, image_a, image_b.
• Term = the keyword, only for paid search when not auto-tagged.

Write the allowed medium values down and do not invent new ones on the fly. Medium is the parameter GA4 relies on most heavily for channel grouping, as explained below.

Keep a log

A shared spreadsheet with columns for date, destination URL, source, medium, campaign, content, full tagged URL and owner prevents duplicates and makes it easy to reuse the same values. It also helps when you need to explain a spike in a report weeks later.

Worked examples

These are illustrative examples using the convention above and the placeholder domain example.com.

Monthly email newsletter with two links to the same offer

• https://example.com/offer/?utm_source=newsletter&utm_medium=email&utm_campaign=october_offer_2026&utm_content=header_button
• https://example.com/offer/?utm_source=newsletter&utm_medium=email&utm_campaign=october_offer_2026&utm_content=footer_link

The only difference is utm_content, so you can compare which link drove more visits and conversions.

Organic LinkedIn post

https://example.com/guide/?utm_source=linkedin&utm_medium=social&utm_campaign=pricing_guide_launch

Paid Facebook ad with two images

https://example.com/landing/?utm_source=facebook&utm_medium=paid_social&utm_campaign=spring_sale_2026&utm_content=image_a

QR code on a printed flyer

https://example.com/visit/?utm_source=flyer&utm_medium=qr&utm_campaign=open_day_2026

Offline campaigns are where UTMs are especially useful, because without them those visits usually appear as direct traffic.

How UTM values appear in GA4

At the time of writing, Google's documentation says you can see campaign data in the Acquisition > Traffic acquisition report using dimensions such as Session source/medium, Session medium, Session source and Session campaign. Menu names and report layouts change from time to time, so check the current interface if yours looks different.

Default channel groups depend on your medium values

GA4 sorts traffic into default channel groups (such as Email, Paid Search, Organic Social and Referral) using rules based largely on source and medium. At the time of writing, Google's channel group documentation includes rules like these (simplified):

• Email: source or medium matches email, e-mail, e_mail or e mail.
• Paid Search: source matches a list of search sites and medium matches a pattern that includes values containing cp (such as cpc), ppc, retargeting, or values starting with paid.
• Paid Social: source matches a list of social sites and medium matches the same paid pattern.
• Organic Social: source matches a list of social sites, or medium is one of social, social-network, social-media, sm, social network or social media.
• Referral: medium is referral, app or link.
• Affiliates: medium is affiliate.
• Display: medium is one of display, banner, expandable, interstitial or cpm.
• Unassigned: used when no other channel rule matches.

This has a practical consequence: if you invent a medium like newsletter_blast or fb_ads, GA4 may not recognise it, and the traffic can end up as Unassigned. Choosing medium values that match these rules, such as email, cpc, paid_social or social, keeps channel reports meaningful. Check the current channel group definitions in Google's help centre before finalising your list, since the rules and source lists can be updated.

Common mistakes

Tagging internal links. Never add UTMs to links between pages of your own site. Doing so can overwrite the original source of the visit and distort attribution. UTMs are for links from outside your site to your site.

Mixed case and spelling. Email, email and e-mail create separate rows in some reports and can even fall into different channels. Pick one and stick to it.

Putting the campaign name in the source. Source should describe where the click came from, not what you are promoting. utm_source=spring_sale makes source reports hard to read.

Leaving out medium. Without a medium, GA4 has much less to go on for channel grouping.

Using UTMs where platforms tag automatically. Some ad platforms support automatic tagging. For example, Google Ads can link with GA4 and pass campaign information automatically. Adding manual UTMs on top can cause conflicts, depending on your settings. Check each platform's current documentation before adding manual tags to paid links.

Sharing tagged URLs publicly in the wrong place. If a tagged newsletter link gets copied into a forum post, visits from that forum will be attributed to your newsletter. Where possible, share untagged links for general use and create separate tagged links for each channel.

Including personal data. Do not put email addresses, names or other personal information in UTM values. URLs can be logged and shared widely, and analytics platforms generally prohibit sending personally identifiable information.

Broken URLs. If the destination URL already contains a question mark, additional parameters must be joined with an ampersand (&), not a second question mark. A link builder handles this automatically.

Checklist before you launch a campaign

• Every external link in the campaign has source, medium and campaign set.
• All values are lowercase and use your agreed separator.
• Medium values come from your approved list and match GA4 channel rules where possible.
• Different creatives or placements use distinct utm_content values.
• No internal links carry UTMs.
• No personal data appears in any parameter.
• Each tagged link has been clicked once to confirm it loads the right page.
• The link is recorded in your shared UTM log.
• After launch, you have checked real-time or traffic acquisition reports to confirm the values appear as expected.

Summary

• UTM parameters label inbound links so analytics can attribute visits to the source, medium and campaign you choose.
• Google's documentation recommends always using utm_source, utm_medium and utm_campaign, and notes that values are case sensitive.
• A simple written convention (lowercase, underscores, a fixed list of mediums) keeps reports clean.
• In GA4, medium values drive default channel grouping, so non-standard mediums can end up as Unassigned.
• Avoid tagging internal links, mixing case, or putting personal data in parameters.

Build consistent links with the UTM link builder, and once conversions are flowing, compare channel returns with the ROAS calculator.

Sources: Google Analytics Help articles on URL builders and campaign parameters (support.google.com/analytics/answer/10917952) and on default channel groups (support.google.com/analytics/answer/9756891), checked at the time of writing. Interface names and channel rules may change; check the current documentation.