Year dimension
Year is the dimension that groups events by four-digit calendar year in the property time zone. On its own it is rarely used, but combined with month or week it labels long-range trends and powers year-over-year comparisons. Long historical analysis is bounded by GA4's event-data retention setting, which caps how far back exploration-level data goes regardless of the year requested.
What this means
The year dimension assigns each event its four-digit calendar year in the property time zone. Used alone it is coarse; its value comes from pairing with month or week to build year-over-year views and multi-year trend lines.
It is the anchor for any comparison that spans annual cycles.
Retention boundary
GA4's event-data retention setting (a fixed maximum number of months) governs how far back exploration and user-level analyses can reach. Aggregated standard reports retain longer, but detailed year-over-year exploration of old years can return nothing once the underlying events have aged out.
So a sparse early year may reflect retention, not history. Confirm the retention setting before concluding traffic was low.
- Four-digit calendar year in property time zone
- Pairs with month/week for YoY views
- Old detail bounded by data-retention setting
How it appears in analytics and logs
A year value is the calendar year of an event. Empty older years often mean event-level data has aged out under the retention setting, not that traffic was zero.
Diagnostic use case
Use the year dimension with month or week to label and compare across years, within the limits of your GA4 data-retention setting.
What WebmasterID can help detect
WebmasterID can bucket events by year first-party for long-range trends, subject to your own retention choices rather than third-party limits.
Common mistakes
- Reading retention-expired years as zero traffic.
- Using year alone where year+month is needed.
- Ignoring the property time zone at the year boundary.
Privacy and accuracy notes
The year dimension records timing, not identity. WebmasterID aggregates by year first-party without retaining personal profiles.
Related pages
- Month dimension
Month is the dimension that groups events by calendar month (01–12) in the property time zone. It is the coarse grain for seasonal and budget-cycle reporting. Its main pitfall is that months have different lengths, so raw month-over-month comparisons mix a 28-day February with a 31-day March, which can masquerade as a trend if you do not normalise per day.
- Date and time dimensions
Date and time in GA4 are a family of dimensions — date, hour, minute and combinations — that stamp each event with when it occurred, expressed in the property's reporting time zone rather than the visitor's local time or UTC. They are the backbone of every trend line. Because the boundary of a 'day' depends on the configured time zone, changing it shifts which events fall on which calendar date.
- Bot traffic in analytics: filtering it out
Bots — crawlers, scrapers, monitors, scanners — generate requests that, unfiltered, inflate pageviews and distort every metric. Client-side analytics often misses bots (many do not run JavaScript) or miscounts the ones that do. Server-side classification at ingest is the reliable way to keep bot traffic out of human reports.
- Web analytics
Year-over-year reporting first-party.
Sources and verification notes
- Google Analytics Help — [GA4] Data-retention settingsDocuments event-data retention bounds on detailed analysis.
- Google Analytics Help — [GA4] Dimensions, metrics, and other termsDefines the year dimension in the property time zone.
Last reviewed 2026-06-24. Facts are checked against primary/official sources where available; uncertain specifics are marked “Data not yet verified” rather than guessed.