The default channel group is the set of rules Google Analytics 4 uses to sort every visit into a marketing channel, such as Organic Search, Paid Social, Email or Direct. It is what you see in the main acquisition reports, and it decides which channel is credited with your enquiries and sales.
How the default channel group works
GA4 reads the source, medium and campaign attached to each visit and checks them against a fixed list of rules, in order. Some rules are simple: a medium of “email” goes to Email and a medium of “referral” goes to Referral. Others combine a medium pattern with lists Google maintains of which websites count as search engines, social networks, shopping sites or video platforms. A visit from facebook.com with a paid-looking medium such as “cpc” or “paid_social” lands in Paid Social, while the same source with a medium of “social” lands in Organic Social. Auto-tagged clicks on Google search ads go to Paid Search, while Performance Max, which runs across several Google networks, goes to Cross-network.
Anything that matches no rule is filed as Unassigned, and visits with no source information at all become Direct.
GA4 applies the rules at more than one level, which is why you will see variants of the same idea. The session default channel group describes what brought each visit, while the first user default channel group describes what first brought each person to the site.
You cannot edit the default rules. If they do not fit your business, you create a custom channel group alongside them, and GA4 applies it to past data as well. At the time of writing (October 2026), both are managed under Admin, then Data display, then Channel groups.
Why it matters
Channel reports are where most budget conversations start. If paid Facebook traffic is filed as Organic Social, your paid campaigns look weaker and your unpaid posting looks stronger than either really is. If your newsletter links carry a medium of “newsletter” instead of “email”, the visits usually land in Unassigned, and email looks as though it produces nothing at all.
Because the rules depend entirely on how links are tagged, the quality of the channel report is set by whoever builds your campaign URLs. In many businesses that is several different people and agencies, each with their own habits.
Common mistakes
- Inventing medium values such as “newsletter”, “fb” or “paid” that match none of GA4’s rules.
- Tagging paid social ads with a medium of “social”, which files them as unpaid.
- Not listing payment providers or booking systems as unwanted referrals, so sales are credited to Referral instead of the channel that brought the customer.
- Adding campaign tags to internal links on your own site, such as homepage banners, which overwrites the real source and hands the credit to your own pages.
- Judging a channel on the session view when the question is really how customers first found you.
How to act on it
Agree a short tagging standard and share it with everyone who builds links: lower-case values, a utm_medium taken from GA4’s recognised list (cpc or paid_social for paid ads, email for email, social for unpaid posts) and one consistent source name per platform. A UTM link builder keeps everyone to the same format.
Then open the traffic acquisition report and look at the Unassigned row. Each source and medium listed there tells you which links need retagging. If your business has a channel GA4 does not recognise, such as a partner referral scheme or printed QR codes, create a custom channel group for it rather than bending the default. Clean channel data is the foundation of my performance marketing reporting.