Measuring traffic from AI tools in GA4

When a client asks us “are people finding us through ChatGPT?”, the honest first answer is usually “some are, and your reports are hiding most of them”. AI visits get scattered across Referral, Direct and Unassigned, and unless someone has set GA4 up to look for them, they just blur into the background.

The good news is that this takes about 15 minutes to fix, and once it’s done you can see AI traffic as its own line in your acquisition reports, going back in time.

What GA4 does out of the box now

In May 2026 Google added an AI Assistant channel to GA4’s default channel group. According to Google’s traffic source dimensions documentation, it covers visitors arriving “from sources like ChatGPT, Gemini, Deepseek, Copilot, or Grok”, and it explicitly excludes Google’s own AI Overviews and AI Mode.

That’s a useful start, but in practice it leaves gaps:

• Perplexity isn’t on Google’s named list at the time of writing (November 2026), so those visits tend to land in Referral.
• ChatGPT visits without a recognised medium can show up as chatgpt.com / (not set), which GA4 drops into Unassigned.
• History before the channel switched on for your property isn’t tagged, so a month-on-month comparison across that date is misleading.
• App traffic often arrives with no referrer at all. Someone taps a link inside the ChatGPT or Perplexity phone app, and GA4 records it as Direct. Nothing you set up will recover those.
• Google AI Overviews and AI Mode count as Organic Search. They come through as google / organic, the same as an ordinary search click.

So the default channel is a floor, not a count. If you want a fuller picture, build your own.

Step 1: see what’s already there

Before changing anything, have a look at what’s coming in. In GA4 go to Reports > Acquisition > Traffic acquisition, change the primary dimension from “Session default channel group” to Session source / medium, and type a few names into the search box above the table: chatgpt, perplexity, gemini, copilot, claude.

On most small business sites we manage, the numbers here are modest. A trade business might see a handful of sessions a month from ChatGPT. That’s fine. The point is to have the line in place so you can see whether it grows, and which pages people land on when it does.

We’ve also seen ChatGPT tag many of its outbound links with utm_source=chatgpt.com, so that may be what you see as the source even when the referrer was stripped.

Step 2: build a custom channel group

GA4 lets standard (free) properties have two custom channel groups on top of the default, and they apply to your reports retroactively. The steps from Google’s custom channel groups help page:

1. Go to Admin > Data display > Channel groups. You need Editor access or higher on the property.
2. Click Create new channel group. This makes a copy of the default group, which is what you want, because you only need to add one channel and leave the rest alone.
3. Name it something obvious, like “Channels incl. AI”.
4. Click Add new channel, call it “AI tools”, and set the condition to Source matches regex with the pattern below.
5. Move the new channel above Referral, Direct and Unassigned. This is the step people miss. GA4 assigns each session to the first channel in the list that it matches, so if Referral sits above your AI channel, Perplexity visits will keep going to Referral.
6. Click Apply, then Save group.

This pattern covers the main tools at the time of writing:

.*(chatgpt\.com|openai\.com|perplexity|gemini\.google\.com|copilot\.microsoft\.com|claude\.ai|deepseek\.com|grok\.com|meta\.ai).*

A few cautions from setting these up on client properties:

• Don’t use a bare google or bing in the pattern. You’ll swallow all your normal search traffic into the AI channel and your Organic Search numbers will collapse overnight.
• Don’t use short fragments like gpt or ai. They match unrelated referrers (mail.ai-something.com, every site with “gpt” in a subdomain).
• Match on Source, not Medium. AI tools aren’t consistent about medium, so matching source alone catches the (not set) and referral variants together.
• Review it every few months. Tools launch, rebrand and change domains. Check your Referral list for anything new that looks like an AI assistant and add it.

Step 3: use it in your reports

Once saved, go back to Traffic acquisition, click the dropdown on the primary dimension, and you’ll see your new channel group listed alongside the default. Pick it, and “AI tools” appears as a row.

The useful questions to ask of that row aren’t “how many?” but:

• Which landing pages? Add a secondary dimension of Landing page. AI tools tend to send people to specific service pages or articles rather than the homepage, which tells you which content they’re quoting.
• Do they convert? If you’ve set up key events for form submissions and phone clicks, compare the AI row’s key event rate against Organic Search. In our experience, AI visitors are few but often further along in their decision, because the tool has already narrowed the options for them.
• Is it trending? Set the date range to the last 12 months and look at the shape, not the size.

If you don’t have form submissions and call clicks tracked as key events, fix that first. Counting AI visits without knowing whether they enquire is only half the story. Our guide to GA4 for people who don’t want to learn GA4 covers the minimum setup.

What about Google’s own AI answers?

GA4 can’t separate a click from an AI Overview from a click on a normal blue link. Both are google / organic.

For that you need Search Console. Google’s Generative AI performance report shows how often links to your site appeared in AI Overviews and AI Mode, broken down by page, country and device. It’s impressions only, not clicks, but it’s the only first-party view of how Google’s AI features are using your pages. As of late August 2026 Google says it’s available for all sites. If you can’t see it, your site probably hasn’t had enough AI impressions yet.

Reading the numbers sensibly

A few things to keep in mind before anyone gets excited or panics:

The numbers are an undercount, always. Between app traffic arriving as Direct and AI Overviews hiding in Organic, the true influence of AI tools on your enquiries is larger than any GA4 row will show. A customer who asked ChatGPT for “a good electrician in Lennox Head”, then Googled your business name and called you, shows up as a branded search or a direct call. That’s why it’s worth asking new customers how they found you, and writing the answer down.

Small numbers swing wildly. Going from 3 to 9 AI sessions a month is a tripling, and also nine people. Look at it quarterly.

And what the AI tools say matters more than how often they send a click. If you want to know what customers are asking these tools in the first place, our piece on what customers ask AI about local trades is a good companion to this one.

Your 15 minute to-do

Check Session source / medium for AI referrers, create the custom channel group with the regex above, move it above Referral, and set a calendar reminder to review the pattern in three months.

Every site we build through our web design service launches with Google Analytics, Search Console and Bing Webmaster Tools set up. Adding the AI channel group to an existing GA4 property, and reading what the AI row tells you each month, is part of our AI search service.