YouTube Analytics ageGroup now counts viewers YouTube estimates to be under 18
What changed
YouTube's March 9, 2026 Analytics and Reporting APIs revision says the ageGroup dimension (Analytics API) and age_group dimension (Reporting API) now include users that YouTube estimates to be under 18 years old. The dimensions documentation lists age13-17 as a group. YouTube Help explains that an age estimation model decides whether a user is over or under 18 regardless of the birthdate on the account, in several countries including the US, the UK and countries in the European Economic Area. The revision does not say how large the shift is.
What it means
Age breakdowns in YouTube Analytics and Reporting API data now include viewers that YouTube's age estimation model places under 18, so audience age shares can shift compared with older reports.
Who is affected
Analytics and reporting tools that show YouTube audience age, and agencies and brands that use age data for reporting or targeting decisions.
What to do by 9 Mar 2026
Mark a series break at 9 March 2026 in age-group trend charts and avoid comparing age shares across that date without a note.
What this means for you
YouTube tells channel owners roughly how old their viewers are. Before, it only used the age people typed in. Now it also counts people that YouTube guesses are teenagers, even if they said they were older. So the age chart in your reports may suddenly show more young viewers. Your audience did not change overnight; the way YouTube counts did.
The details
- Dimensions:
ageGroup(YouTube Analytics API) andage_group(YouTube Reporting API) "now include users that YouTube estimates to be under 18 years old." - Values: the dimensions page lists groups starting at
age13-17, thenage18-24and older bands. - How the estimate works (YouTube Help): an age estimation model determines whether a user is over or under 18 "regardless of the birthdate in their account", in countries including Australia, Brazil, Canada, the UK, the US and the European Economic Area.
- Not stated: whether past data was reprocessed, and the size of the shift.
What to do next
- Business owners: If your YouTube audience suddenly looks younger since March 2026, this is likely why.
- Marketers and agencies: Add a note to age-based client reports that span 9 March 2026.
- Developers: Flag 2026-03-09 as a methodology change in stored
ageGroupandage_groupseries.
Primary sources
- YouTube Analytics and Reporting APIs: Revision history (March 9, 2026)
- YouTube Analytics API: Dimensions (ageGroup)
- YouTube Help: Understanding age estimation on YouTube
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