You measure it with a small set of imperfect signals rather than one clean number, because no analytics view today reports AI-driven visits with full accuracy. The honest starting point is that you assemble a partial picture from referral data, Search Console patterns, and manual citation checks, then read that picture knowing it understates and misattributes some of what is happening. Anyone promising you a tidy “AI traffic” dashboard is overselling what the tools can currently do.

The first signal is referral traffic from AI tools inside your analytics. Some assistants and AI search surfaces pass a referrer when a user clicks through, so you can filter your acquisition reports for known AI domains and watch whether sessions from those sources rise over time. This captures only the clicks that actually happen and that carry a clean referrer, which is a fraction of total AI exposure, but it is real traffic you can attribute with some confidence.

The second signal lives in Search Console. When your impressions climb while clicks stay flat, that gap is a useful proxy for answers being read without a visit, which is the pattern AI summaries and zero-click results tend to produce. You cannot prove AI caused any single impression, but a widening impressions-without-clicks trend on queries you would expect AI to answer is worth tracking as a directional cue.

The third signal is manual. Periodically ask the major AI tools the questions your pages target and note whether your brand or content gets named or cited. This is slow and unsystematic, but it tells you something the logs cannot: whether you are visible in the answer itself even when no click follows. Citations there are visibility, not sessions, so treat them as a separate column from your referral numbers. All of this is worth re-checking, since AI attribution and the referrers these tools send are still shifting and any method here may improve or break within months.

To start, set up the AI-referral filter in analytics, save an impressions-versus-clicks view in Search Console for your key queries, and put a recurring reminder to spot-check citations by hand, then read each signal for what it is and accept that the gaps are part of the measurement, not a flaw you can fix.