Ask three analytics vendors how much of your AI referral traffic comes from ChatGPT and you will get three different answers: 92%, 78%, and 63%. All three are honest. They measure different sites and weight them differently, and the gap between them is the most useful thing in this data.
The Three Studies
| Platform | Previsible (session-weighted, Nov 2024 to May 2026) | SE Ranking (Jan 2025 to Apr 2026) | Goodie (brand-averaged, Mar to Apr 2026) |
|---|---|---|---|
| ChatGPT | 92.4% | 78.23% | 62.6% |
| Claude | Overtook Perplexity in March 2026 | 1.40% | 18.5% |
| Gemini | Growing, ~3.2x over the window | 6.85% | 10.6% |
| Perplexity | Down 61% from its March 2025 peak | 9.33% | 7.3% |
| Copilot | Down 96% from its August 2025 peak | 3.57% | 4.0% |
| Panel | 166 GA4 properties, 6.77M sessions | 101,574 websites | Anonymised brand panel |
Why They Disagree
Weighting. Previsible counts sessions, so a handful of high-traffic sites dominate and ChatGPT's scale shows at full strength. Goodie averages each brand's share with every brand counted equally, so a B2B software company where Claude sends a third of AI visits moves the result as much as a retailer with ten times the traffic. That is also why Goodie's five shares sum to 103% rather than 100%.
Time window. SE Ranking's 78% covers sixteen months, most of it before Claude's growth started. Its own month-by-month data shows Claude's share of all web traffic rising 386% between January and April 2026, a trend that a sixteen-month average flattens.
Audience. Claude's users skew toward developers and knowledge workers. Sites that sell to that audience see Claude far above its average share. Consumer retail sites see it far below.
What Is Consistent Across All Three
- ChatGPT is still the largest single source of AI referrals everywhere, and in May 2026 alone it sent 610,910 of Previsible's 644,478 monthly LLM sessions.
- Claude is the fastest-growing source in every dataset that reports growth. Previsible measured 64x growth in Claude referral sessions over nineteen months.
- Perplexity and Copilot referral volumes fell in the session-weighted data during 2026 even as their shares held up in brand-averaged data.
- AI referrals are still small next to search. Even the highest-penetration vertical in Previsible's panel, insurance, got 1.51% of its sessions from LLMs by May 2026.
Which Number To Use
If you sell to consumers at scale, the session-weighted view (ChatGPT around 90%) is closer to what your analytics will show. If you are a B2B, developer, or professional-services brand, the brand-averaged view is the better prior, and you should expect Claude to be a real second source. In both cases your own GA4 data beats any panel. Segment referrals by chatgpt.com, claude.ai, gemini.google.com, perplexity.ai, and copilot.microsoft.com before you set platform priorities.
Brand Visibility Implications
Referral share is a lagging indicator of recommendation share. A platform only sends a click after it has mentioned you, so a brand that is absent from Claude answers will see no Claude referrals and may wrongly conclude Claude does not matter for its category. Measure mention rate on each platform first, then use referral share to size the prize. The volatility is also real: Previsible recorded a month in which ChatGPT referrals dropped from 448,412 to 213,345 sessions after a model change, which is why single-month comparisons mislead. See Claude referral traffic growth and ChatGPT market share erosion.
Methodology
Figures come from published first-party and panel studies, each cited at the point of use: Google's I/O 2026 keynote and Q2 2026 earnings remarks, Previsible's AI Traffic Report, SE Ranking's Claude traffic research, Goodie's AI Search Traffic Report, Seer Interactive, Ahrefs, Pew Research Center, and Semrush. We report each study's own date range next to its numbers because these studies measure different panels over different windows. Where they disagree, we show the disagreement rather than averaging it away. Figures are as of September 2026 and are reviewed quarterly.
How Presenc AI Helps
Presenc AI tracks how often each AI platform mentions and recommends your brand on the prompts your buyers use, so you can tell whether a low referral share means a small platform or a visibility gap you can fix.