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.
What this means
The month dimension assigns each event its calendar month, computed in the property time zone. It is the natural grain for seasonality, budget periods, and high-level executive summaries where daily detail is noise.
Reports often pair it with year to give a full year-month label.
Unequal-length pitfall
Calendar months span 28 to 31 days, so a raw count comparison between months partly measures how many days each contains. A February-to-March rise can be entirely explained by three extra days. Normalising to a per-day average removes that distortion.
The same caution applies to partial current months, whose totals are incomplete until the month ends.
- Calendar month 01–12 in property time zone
- Months differ in length — normalise per day
- Current month is partial until it closes
How it appears in analytics and logs
A month value is the calendar month of an event. A month-over-month change can be an artefact of differing month lengths rather than a real shift.
Diagnostic use case
Use the month dimension for seasonal and budget-cycle reporting, normalising per-day when comparing months of unequal length.
What WebmasterID can help detect
WebmasterID can bucket events by calendar month first-party, supporting seasonal reporting without third-party tracking.
Common mistakes
- Comparing month totals without adjusting for month length.
- Reading a partial current month as a full-month decline.
- Forgetting the property time zone defines the month boundary.
Privacy and accuracy notes
The month dimension records timing, not identity. WebmasterID aggregates events by month first-party without profiling visitors.
Related pages
- Week dimension
Week is the dimension that groups events by the numbered week of the year (01–53). In GA4 the week begins on Sunday, so the first and last weeks of a year are usually partial. It smooths daily noise into a steadier trend, but the Sunday boundary and partial-week edges mean its counts are not directly comparable to ISO-week tools that start on Monday.
- 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.
- Nth month dimension
Nth month is the dimension that numbers months by their offset from the start of the selected range — month 0, month 1, and so on. It is the longest-horizon member of the nth-period family, built for lifecycle and long-term cohort analysis where retention is measured over many months. Its numbering is relative to the report range, and like its siblings it carries no fixed calendar meaning.
- Web analytics
Seasonal reporting first-party.
Sources and verification notes
- Google Analytics Help — [GA4] Dimensions, metrics, and other termsDefines the month 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.