Key points
- Graphite's updated report, using Similarweb estimates, counts 76 billion monthly sessions across six AI assistants in September, up 37% year over year.
- Graphite dropped its March comparison of AI use to search, saying it likely undercounted Google's Android app, an estimated 11.8 billion monthly U.S. sessions.
- AI referrals make up under 1% of website traffic on average; U.S. organic search was 49 times AI referral volume in Q2 2026.
- ChatGPT drove 60% of global AI referral traffic in July; Claude grew 1,901% in sessions, while Perplexity fell 27%.
Why it matters for marketers: Any AI-versus-search ratio in a channel plan depends on how Google was counted, and AI referrals still send little traffic, so budgets should rest on your own analytics.
Graphite, an agency that sells SEO and AEO services, updated its AI usage report with Similarweb estimates showing six AI assistants at 76 billion sessions worldwide in September, up 37% from a year earlier. The new edition leaves out the March comparison of AI use with search engines.
The reason is a counting problem. The March figures measured search through website visits only, on the view that apps saw little use. Graphite now says the Google Android app is large, at an estimated 11.8 billion monthly U.S. sessions, and is used for translation, image recognition and Discover as well as search. It says it has no reliable source to split out the search share, so it can no longer reliably compare the two. Per the source article, the March page still highlights the older figures, with a link to the new report.
For marketers, the referral data is the more practical part. AI accounts for less than 1% of traffic to sites on average, and U.S. organic search was 49 times the volume of AI referrals in the second quarter of 2026. Referrals are growing from that small base, up 92% worldwide and 75% in the U.S. as of July. ChatGPT supplied 60% of global AI referrals, with Gemini at 14% and Claude at 10%.
Graphite also notes anecdotal evidence that some AI-prompted visits are credited to direct or branded search, which referral reports would miss. Its early data shows branded search roughly flat year over year, with full results to come. Teams tracking AI influence may want to look at branded and unbranded queries alongside referrals, and to check how any AI-to-search ratio counted Google before using it in a plan.
Sources
This brief is our own summary. Read the full reporting at the source.