6,333 Brands In, ChatGPT Ads Still Convert at a Third of Google

Paid ChatGPT traffic converts at 0.37%, versus 1.17% for paid Google Search visits — and generates $0.89 in revenue per session for U.S. advertisers, compared with $2.45 on Google. Those numbers come from a working paper under review by Maximilian Kaiser and Christian Schulze, based on data from ecommerce websites, and they land as the number of brands advertising on ChatGPT approaches 6,000.

OpenAI only started selling ads this year, and advertising is lagging usage. ChatGPT now handles roughly a fifth of the search queries Google does, but its ads business is worth considerably less. Advertisers are already testing how fast that can change.

How many eligible users actually see ads?

Fewer than half of ad-eligible ChatGPT users see ads even in OpenAI's most established markets, according to Similarweb and Graphite data:

• U.K.: 45.7% of ad-eligible users reached
• U.S.: 43.4%
• Australia: 43.3%
• Mexico: just 27.8%

The gaps could reflect how far along each market is in the rollout, or how much of its eligible audience OpenAI currently monetizes. Either way, OpenAI has room to grow reach inside markets where it already operates.

Is advertiser spend broadening beyond retail?

Yes, and quickly. Sensor Tower data shows shopping fell from 38% of U.S. ad spend on ChatGPT in April to 20% by September. Over the same period:

• Financial services grew from 2% to 13%
• Software grew from 13% to 18%
• Travel and tourism increased from 5% to 9%

At the pilot's launch in February, the mix was far narrower: roughly 42% of ads came from shopping advertisers, followed by jobs & education (10%), food & dining (9%), software (8%), media and entertainment (8%) and travel (7%). ChatGPT is no longer depending on a narrow set of verticals chasing shopping moments.

How fast is the advertiser base growing?

Fast. Adthena tracked 1,082 distinct brands running ads across the U.S., Australia, the U.K. and the EU in June. That rose to 3,741 in July and 6,333 in August. September data, tracked through Sept. 20, is projected to reach around 6,830 for the full month.

What would scaling the economics require?

New Street Research models commercial chats on ChatGPT growing from 45.9 billion this year to nearly 380 billion by 2030, with the share of total chats carrying ads rising from 20% to 28%.

OpenAI recently said CPC and outcome-optimized bidding account for the majority of its ad campaigns — a higher proportion than New Street had assumed. That matters because CPC ads typically generate more per ad event than impression-based pricing. But New Street cautions monetization may currently be weaker than it modelled, and its estimated CPC of around $5 could be too high.

Measurement problems compound the performance questions. Farhad Divecha, group CEO of Accuracst, said the latest partner integrations — Magnite and Pubmatic — have not necessarily fixed underlying tracking issues.

"We continue to see discrepancies there," Divecha said. "Some are teething problems because it's a new system that has to be set up on advertiser systems, but some problems are down to attribution being messed up."

The takeaway in plain words: thousands of brands are testing ChatGPT ads, but until conversion and attribution gaps close, OpenAI still has to prove its ads can compete with established performance channels.