Measure AI traffic in GA4: does ChatGPT send customers?

Google introduced the AI Assistant channel on 13 May 2026 in GA4’s default channel group. Recognised AI referrals receive medium ai-assistant and campaign name (ai-assistant).

Check this channel in acquisition reports first. Custom groups are optional for additional classifications; using the default channel requires no custom group. Google’s channel definitions also distinguish Google AI Overviews and AI Mode clicks: these belong to Organic Search, not AI Assistant.

You can investigate visitors and results from recognised AI traffic. Without an identifiable referrer, this classification cannot recover missing origins.

First, adjust expectations: the hype is ahead of the figures. In Conductor’s industry benchmark, AI accounts for 1,08 percent of all website traffic. This rises to 2,80 percent in IT and remains at 0,25 percent in communication services. For an average Belgian small business, that means a few percent rather than a seismic shift.

Growth is impressive, though. Contentsquare measured 632 percent year-on-year growth in AI traffic, starting from 0,2 percent of all traffic in the fourth quarter of 2025. Start measuring today and you will have a series of figures to build on within a year. Wait and you start from zero next year.

Who sends that traffic? ChatGPT remains dominant at 87,4 percent of all AI referrals according to Conductor. BrightEdge saw Gemini rise to 13,2 percent in April 2026. For your channel group, ChatGPT and Gemini are the two names that really matter; include the rest for completeness.

This is where it gets interesting. AI visitors are few, but behave differently. The Digital Bloom figures collected in the same benchmark show a clear difference:

The logic is simple. Someone arriving through an AI assistant has already discussed their problem. The AI weighed the options and mentioned your name. They are not coming to browse: they arrive with a question. That explains the long sessions and high conversion rate.

The practical consequence: one percent AI traffic can deliver as much as ten percent ordinary search traffic. That is precisely why leaving it in a catch-all category is a waste.

Start with the default channel. Create an additional custom group only when another classification is needed:

1. Open acquisition reports and find AI Assistant in the default channel group. Use matching periods and key events for other channels.
2. Check source and medium. Recognised traffic uses medium ai-assistant. Investigate deviations before adding rules.
3. If necessary, create a custom group in Admin. Choose additional AI sources to distinguish and test rules against actual source values.
4. Place your AI rule before Referrals if both would catch the same traffic. Google explains this in its custom channel-group guide.
5. Compare visitors and key events by channel. Keep measured referrers separate from visitors’ self-reported origins.

Also ask enquirers how they found you. These provide additional clues, not automatically measured click origins.

Channel classification uses available origin data. Without a recognisable referrer, GA4 cannot automatically attribute visits to AI assistants. We found no verifiable primary method supporting previously cited invisible-AI percentages, so we no longer use them.

Rising Direct traffic therefore does not prove rising AI traffic. Direct visits to deep pages can likewise come through multiple unidentified routes.

What you can do:

• Investigate Direct changes. Check campaign labels and referrers without automatically calling remaining visits AI.
• Inspect landing pages. They help investigate behaviour but cannot prove which service sent visits without origin signals.
• Use self-reporting as supplementary indication. Keep it separate from measured referrers and disclose limitations in conclusions.

Measurement is not an end in itself. What changes in your approach once AI traffic becomes visible?

1. Write pages an AI can cite. Concrete figures, clear answers to real questions and an FAQ with complete sentences. AI assistants like citing clearly defined facts rather than vague sales language.
2. Make your business findable, not just your website. An accurate, complete Google Business Profile, consistent listings on Belgian industry sites and clear contact details on your .be domain help AI tools describe you correctly.
3. Compare quarterly, not weekly. With only a few percent of traffic, week-to-week fluctuations exceed the signal.
4. Do not assign a budget you cannot justify. AI visibility largely results from good content and good discoverability, work that also pays off in ordinary search results.

Visible AI traffic converts at 1,66 percent versus 0,15 percent for organic search traffic. There are few visitors, but they are the right ones.

Want to know whether your website is ready to be found and correctly described by AI assistants, and whether your measurement actually captures those visitors? Run Marketing Scan’s free marketing scan. Within minutes you receive a clear report on discoverability, your measurement setup and the points offering the quickest gains.