GA4 Annotations: Marking Changes on Report Charts
A GA4 annotation is a short note pinned to a date on your report charts: a site launch, a campaign start, a tracking fix. This guide covers who can add them, the limits, where they appear, the annotations Google adds itself, the Admin API, and the habits that make them useful months later.
This guide is based on Google's Analytics Help pages on annotations and access roles, the Admin API reference for reporting data annotations and the Search Central post on Search Console custom annotations, as published in November 2026. Where we give our own advice, we say so.
What annotations are for
Google describes annotations as a way to "add notes directly to Google Analytics 4 reports", to "record events, explain changes in data, or highlight key observations for yourself and your team." Its own examples are spikes or dips in traffic, marketing campaign launches and product launches.
The value shows up later. Six months from now, nobody remembers the week the contact form broke or the day a newsletter went out. A note on the chart answers "what happened here?" before anyone starts digging. How annotations fit into a monthly client report is covered in our website analytics reporting guide; this page covers how the GA4 feature itself works.
Who can add and see them
Annotations belong to the property, not to one person. Google's rules:
- You must be "an Analyst or above at the property level to create, edit, and delete annotations".
- You need "a Viewer or above to view annotations."
- "Each property has a limit of 1000 annotations."
- Annotations can be created in Reports with line graphs or through the Admin API.
In GA4's role list, Analyst sits above Viewer and below Editor and Marketer, and both of those include the Analyst permissions. So everyone except Viewers can annotate. If a client gives you Viewer access only, you can read their notes but not add your own; ask for Analyst if you are expected to keep the record.
Our tip: since every user on the property can read them, keep annotations factual and free of personal details, client contract terms or anything you would not show the whole team.
Adding an annotation
Google's steps:
- Click Reports on the left and open the report you want.
- Right-click any data point on any line graph.
- Click Add annotation.
- Fill in the details and click Create annotation.
| Field | What Google allows |
|---|---|
| Title | Up to 60 characters |
| Description | Up to 150 characters |
| Date | A single date or a date range |
| Colour | Chosen from a set of colours |
Ranges are handy for a campaign that runs two weeks, but Google adds a caution: "If you're anticipating having a high number of annotations with overlapping date ranges, it's recommended to create annotations for a single date instead." Many overlapping bars make a chart hard to read. Our habit is to mark the start and the end of a long campaign as two single-date notes when the chart is already busy.
Where annotations show up
An annotation is not tied to the report you created it in. Google says it is "visible across all reports and report cards with line graphs." So a note added on the Traffic acquisition chart also shows on other line charts and report cards that cover the same dates.
- On the chart: an icon appears below the line graph. Hover over it for a card with the details, or click it to open the Annotations Viewer panel.
- In Admin: under Data display, click Annotations to see every annotation on the property. Depending on your access level, Google says you may be able to "create, edit, delete, or export" them there. This list is the easiest place to tidy up old notes.
- Hiding them: at the bottom left of the Annotations Viewer panel, Annotations Settings has a toggle that hides or shows all annotations and the bars for date ranges. The setting applies to all annotations at once, not one by one.
Annotations are notes only. They do not change any numbers, filter data or affect what GA4 collects.
Annotations Google adds
Google Analytics can add annotations of its own. Google's page says: "When a significant data-impacting event occurs, Google Analytics may create an annotation to notify users about the issue on the relevant date and data." They look like user annotations, "except that they can't be edited or deleted."
When you see an unexpected dip, check for one of these first. If Google has marked the date, the cause may be on Google's side rather than on your site. If there is none, look at your own changes: a new release, a consent banner update, a tag removed in Google Tag Manager, or internal traffic suddenly counted.
Annotations through the Admin API
The Admin API exposes annotations as a resource called reportingDataAnnotations, documented under the v1alpha version of the API. Points from the reference:
- The methods are create, delete, get, list and patch.
- Each annotation has a required title and colour, an optional description, and either a single date or a date range. The date "may be in the past, present, or future."
- Date ranges include both the start and end date, and "Time zones are based on the parent property."
- The colours are purple, brown, blue, green, red, cyan and orange, and orange is "Only used for system-generated annotations".
- A systemGenerated field is true for annotations Google created; "System-generated annotations cannot be updated or deleted."
For an agency this opens a few practical options. A deploy script can add a note when a new site version goes live, and a list call can pull every note into a report or a spreadsheet. Because the API is an alpha version, expect it to change; check the reference before building on it.
GA4, Search Console and Google Ads
Annotations do not travel between Google tools. Search Console added its own custom annotations to the Performance reports in November 2025: right-click the chart, choose Add annotation and write a note "up to 120 characters" with a date. Google notes there that "everyone with access to your Search Console property will be able to see your custom annotations".
| GA4 annotations | Search Console annotations | |
|---|---|---|
| Where | Line charts across Reports | Performance report charts |
| Text | Title 60 + description 150 characters | Note up to 120 characters |
| Date | Single date or range | A specific date |
| Who sees them | Viewer or above | Everyone with access to the property |
Google Ads keeps its own record too: it logs account edits automatically in change history. That log tells you what changed in the ad account; a GA4 annotation is where you note that change next to the website data.
What to annotate and how
This section is our own practice, not Google's guidance. Things worth a note on the day they happen:
- Site launches, redesigns, URL changes and migrations.
- Tracking changes: a new tag, a changed key event, a consent banner update, an internal traffic filter switched on.
- Campaign starts and ends, newsletters, press mentions and price changes.
- Outages, broken forms or checkout problems, with the date they were fixed.
- Outside events that move demand, such as holidays or a local event.
A few habits keep the record readable:
- Start the title with the type: for example "Tracking: form event renamed" or "Campaign: spring sale". With 60 characters, short prefixes leave room for the rest.
- Use colours consistently: one colour per type, written down for the team. Leave orange alone, since the API reserves it for Google's own notes.
- Say who and where: the description can hold a ticket number or the name of the team that made the change.
- Mark it in both tools: a change that can affect search traffic goes in Search Console too.
- Hand them over: annotations stay with the property, so they survive a change of agency as long as the property does.
If GA4 itself is new to you, start with our GA4 guide for small business websites.
Frequently asked questions
Who can add annotations in GA4?
Users with the Analyst role or above on the property can create, edit and delete annotations. Viewers can see them.
How many annotations can a GA4 property have?
Google sets a limit of 1,000 annotations per property.
How long can an annotation be?
The title can be up to 60 characters and the description up to 150 characters.
Can I delete an annotation that Google added?
No. Annotations created by Google Analytics look like your own but cannot be edited or deleted. In the Admin API they are marked as system generated and use the orange colour.
Do GA4 annotations show in Search Console?
No. Search Console has its own annotations on its Performance reports, with a 120-character note and a date, so a change worth marking usually goes in both tools.
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