What UTM parameters do
UTM parameters are small tags added to the end of a URL that tell your analytics where a visitor came from. Without them, a click from your email newsletter and a click from a LinkedIn post can both land in GA4 as vague "direct" or "referral" traffic, and you never learn which effort actually worked. With them, every campaign link carries its own label, so the traffic report reads like a ledger: this many visits from the newsletter, this many from the spring ad, this many from the partner blog. The name comes from Urchin Tracking Module, the software Google bought and turned into Google Analytics, and the format has been the industry standard ever since.
This tool builds tagged links entirely in your browser. Nothing you type is uploaded, stored or sent anywhere.
The conventions that keep reports clean
Each parameter answers one question, and mixing the questions up is the fastest way to ruin a report. The working shorthand: source is where, medium is how, campaign is why.
- utm_source = where the link lives: newsletter, google, linkedin, partner-blog
- utm_medium = how it travels: email, cpc, social, referral, qr
- utm_campaign = why it exists: spring-sale-2026, product-launch, black-friday
- utm_term = the paid keyword, mostly for search ads: fine wine storage
- utm_content = which of several links in the same place: header-button, footer-text
The core trio of source, medium and campaign should appear on every tagged link, because GA4's default channel grouping leans on source and medium to classify traffic at all. Term and content are refinements: term for the keyword behind a paid click, content for telling the button and the text link in the same email apart.
Consistency beats cleverness every time. GA4 treats values as case-sensitive, so Email, email and EMAIL become three separate rows that quietly split one campaign's numbers three ways. Agree a house style, sensibly all lowercase with hyphens instead of spaces, write it down, and never improvise a new name for an old source.
Common mistakes worth avoiding
The classic structural error is bolting parameters on by hand: pasting ?utm_source=... onto a URL that already has a query string produces two question marks and a broken link. This tool parses the URL properly and appends UTM tags to whatever is already there, so existing parameters survive intact.
Note the ref=x survives, and the spaces in the campaign name are encoded as %20 so the link cannot break in transit. Better still, avoid spaces altogether: summer-sale-2026 needs no encoding and reads cleanly in reports.
The other big mistake is tagging links between pages on your own site. UTM parameters restart attribution, so a visitor who arrived from a genuinely useful campaign gets relabelled by your own navigation, and the campaign loses the credit. Tag inbound links only: emails, ads, social posts, QR codes and partner sites.
A workflow that scales
For one or two links, this page is all you need: fill in the trio, copy, paste into the campaign. Once several people are tagging links, keep a shared spreadsheet of every tagged URL with its source, medium and campaign values, so nobody invents email-newsletter when the house style says newsletter. And before a big send, click your own tagged link and watch it arrive in GA4's realtime report: thirty seconds of checking has saved many a month-end reporting headache. If you want to inspect a tagged link someone else built, the URL parser will break it back into its parts.
Frequently asked questions
Which UTM parameters do I actually need?
Source, medium and campaign are the core trio, and GA4 expects all three to make sense of a link. Term and content are optional refinements: term for paid keywords and content for telling two links in the same campaign apart, such as a button versus a text link.
Does capitalisation matter in UTM values?
Yes. GA4 treats values as case-sensitive, so Email, email and EMAIL show up as three separate rows in your reports and split your numbers between them. Pick lowercase for everything and stick to it, which is why this tool warns you when it spots mixed case.
Will tagging break a URL that already has parameters?
Not here. The tool parses your URL properly and appends the UTM parameters after whatever is already in the query string, so a link like example.co.uk/page?ref=x keeps its ref parameter. Bolting UTM text on by hand with a second question mark is what breaks URLs.
Should I tag links between pages on my own site?
No. UTM parameters are for inbound links from elsewhere, such as newsletters, ads and social posts. Tagging internal links restarts the visitor's session attribution, so the campaign that genuinely brought them to your site gets overwritten by your own navigation.
Is my URL uploaded anywhere?
No. The link is built entirely in your browser with JavaScript, so campaign URLs, parameter values and anything else you type never leave your device.