Free GA4 Channel Grouping Validator

The 17-channel order

GA4 evaluates channels in a fixed priority order: Direct → Cross-network → Paid Shopping → Paid Search → Paid Social → Paid Video → Display → Paid Other → Organic Shopping → Organic Social → Organic Search → Organic Video → Email → Affiliates → Referral → Audio → SMS → Mobile Push → Unassigned. The first channel whose rules match wins. This is why a paid-medium google source lands in Paid Search, not Organic Search, even though google is on the search-engine list.

The most common bugs

• medium=newsletter: lands in '(unassigned)'. Use medium=email instead.
• medium=paid: matches the paid regex (^paid.*$) so this works, but custom medium=paid-other lands in 'Paid Other' which is rarely what you want.
• source=Google: GA4 is case-sensitive. 'Google' won't match the search engine list, falls through to Referral.
• medium=social with non-social source: lands in Organic Social if source is on the list, otherwise '(unassigned)'.
• Missing medium: with source set but no medium, GA4 treats it like Direct.

The paid-medium regex

The single most important pattern in GA4 channel grouping is the paid-medium regex: ^(.*cp.*|ppc|paid.*)$. This catches cpc, ppc, paid_social, paid_search, cpm, paid-video, etc. Anything matching this pattern is treated as paid. The trick: 'cpv' matches (because 'cp' appears in it), and so does 'cpa' and 'cpd'. So if you use medium=cpv, you'll end up in Paid Search or Paid Other depending on source. Stick to cpc, ppc, paid_search, paid_social for predictable behavior.

Source lists that matter

GA4 maintains three internal source lists that determine channel grouping for paid and organic traffic:

• Search engines: google, bing, yahoo, duckduckgo, baidu, yandex, naver, ecosia, ask, aol
• Social platforms: facebook, instagram, twitter, x, linkedin, tiktok, pinterest, reddit, snapchat, whatsapp, threads
• Video platforms: youtube, vimeo, twitch, dailymotion, wistia

Sources not on these lists with paid mediums land in 'Paid Other'. With organic mediums, they land in 'Referral'.

Custom Channel Groups vs Default

If your team uses non-standard mediums (medium=newsletter, medium=podcast, medium=event), you have two choices: rename them to GA4's standard vocabulary at the source, or build a Custom Channel Group in GA4 (Admin → Channel Groups). Custom groups override the Default Channel Group in any report you configure to use them. The Default Channel Group always still runs the original rules though, so legacy reports continue to show '(unassigned)'.

A worked example

Source = facebook, medium = social. GA4 evaluates: not Direct (source is set), not Cross-network (no campaign name), not Paid Shopping (medium doesn't match paid regex), not Paid Search, not Paid Social (medium isn't paid), not Paid Video, not Display (medium isn't display/cpm/banner), not Paid Other, not Organic Shopping (source isn't a shopping site), matches Organic Social (source is on the social list AND medium is non-paid). Final bucket: Organic Social. Change medium to 'paid_social' and the result jumps to Paid Social. Change source to 'Facebook' (capital F) and it doesn't match the social list, falling through to Referral. Same intent, three different buckets depending on small details.