UTM parameters explained with a UK campaign example for GA4

Open Google Analytics for a small UK shop and the biggest source of traffic is usually "direct", which is analytics shorthand for "no idea". Most of it is the newsletter, the Instagram bio, the leaflet and the text message, none of which told GA4 where the visitor came from. UTM parameters are the fix. They are five small additions to a web address that tell analytics exactly which campaign, channel and placement produced the visit.

The five parameters

Source, medium and campaign are the three that matter; content and term are optional. A tagged address looks like this: example.co.uk/black-friday?utm_source=newsletter&utm_medium=email&utm_campaign=black-friday-2026. The UTM link generator builds it from a form so nothing is misspelt.

Rules that keep GA4 reports tidy

• Lower case only. GA4 treats Email and email as two different mediums, and your report splits in half.
• One separator. Hyphens or underscores, never spaces. Pick one and keep it. If a value must contain a space, run it through the URL encoder, but a better answer is to remove the space.
• Use mediums GA4 already understands. email, social, cpc, affiliate, referral, display and sms are sorted into the right default channel automatically. Invented mediums such as insta or flyer land in "Unassigned".
• Never tag links inside your own site. A tagged internal link restarts the session with a false source and wipes the real one.
• Write the convention down. One shared document with the allowed sources and mediums, and one person who owns it.

A worked example, Black Friday for a UK shop

The destination is example.co.uk/black-friday. The campaign name is black-friday-2026 everywhere, and each placement gets its own source, medium and content.

The qr medium will appear under Unassigned unless you create a custom channel group in GA4, but the source and medium are still there to filter on, and that is what you need on the Monday after.

Keep the tagged address out of sight

A tagged address is long and ugly, and nobody types one from a leaflet. Put each tagged destination behind its own short link. digily.uk/bf-leaflet on the leaflet, digily.uk/bf-sms in the text, and the tags travel invisibly with the redirect. Digily Link can also add the UTM parameters for you in the link settings, on every plan, so the destination you paste stays clean and the tags are applied at the moment of the redirect. Either way the visitor sees a short branded address, GA4 sees the full tags, and the link's own statistics record the UTM source, medium and campaign as well as the clicks.

The QR code for the leaflet is generated from the short link, not from the tagged address. That keeps the code simple to scan and lets you change the destination after printing. The guide to branded short links on a .uk domain covers choosing the domain and slug.

Reading the results in GA4

1. Open Reports, then Acquisition, then Traffic acquisition.
2. Change the primary dimension to Session source / medium. Each row is one placement from the table above.
3. Add a secondary dimension of Session campaign, or filter to black-friday-2026, to see the campaign on its own.
4. Compare conversions, not only sessions. A placement that sends fewer visitors who buy more is the one to repeat.

Give the campaign a week before drawing conclusions, and keep the short links live afterwards. A leaflet is scanned for months.

Mistakes that quietly ruin the data

• Mixed capitalisation across the team, so the same source appears three times.
• Sharing a tagged page address by copy and paste, so a WhatsApp forward reports itself as the newsletter.
• Adding UTMs to Google Ads links while auto-tagging is on, which makes the two disagree.
• Using utm_source for the campaign name and utm_campaign for the source. Source is where, medium is how, campaign is what.
• Tagging links that point at someone else's site. Their analytics gets the tags; yours sees nothing.

When a tagged link misbehaves, paste it into the URL parser to see each parameter on its own line, and into the URL redirect checker to confirm the tags survive the redirect.

Tagging the buttons on a bio link page

A bio link page is a set of placements too. Give each button that leads to your site its own utm_content, for example bio-shop, bio-booking and bio-newsletter, with utm_source set to the platform the profile is on and utm_medium=social. Because the same page is linked from Instagram and TikTok, the tags alone cannot tell the two apart; the page's own referrer report does that, and a separate short link per platform in each profile does it more precisely. Keep the campaign name fixed for the page's evergreen buttons and change it only for the top button when it points at a live promotion.

Frequently asked questions

Do UTM parameters affect search rankings?

No. Google ignores them for ranking and treats the tagged address as the same page, as long as the page carries a canonical tag, which nearly every shop platform adds by default.

Can I use them on a bio link page?

Yes. Tag the destination of each button that leads to your own site. Each button on a Digily Link page also counts its own clicks, so you get both views.

Do they work without a consent banner?

UTM parameters are part of the address, not a cookie. GA4 itself needs consent under UK rules; the statistics on Digily Link do not, because they are collected without a tracking cookie.

What is utm_id?

An optional campaign ID that lets GA4 match the visit to a campaign you have defined in its own settings or imported cost data for. Most small businesses never need it.

Should the campaign name include the year?

Yes, if the campaign repeats. black-friday-2026 and black-friday-2027 can be compared; black-friday cannot.

Final checks

• Every placement has its own source, medium and content, all in lower case.
• Mediums are ones GA4 recognises.
• Tagged addresses sit behind short links, and the QR code points at the short link.
• No internal link on your site carries UTM tags.
• The convention is written down where the whole team can see it.