ChatGPT ads now reach 43% of eligible US users. Agencies still spend test money on them

Six months after launch, ads in ChatGPT have been seen by 43% of US users who can be shown them, according to a report by Graphite and Similarweb covered by Search Engine Land on 29 September. The two firms looked at more than 98,000 ads and 8,000 landing pages. Agencies interviewed by Digiday on 1 October say the money behind those ads is still mostly test money.

Graphite saw more than 500 advertisers between April and August

Graphite’s US data covers over 95,000 ads from more than 500 advertisers, placed between 1 April and 16 August 2026. Click-through rates have doubled since launch, the report says. Ads shown in the first few turns of a conversation got the most clicks and impressions.

The best performers wrote almost all of their ad text from scratch: 98% of their copy was new, not reused from other platforms. Half of the top ten advertisers ran more ads on ChatGPT than on Meta. Most advertisers sent people to five landing pages or fewer, usually feature, pricing or product pages. Google Search still carries far more ad volume.

OpenAI says ChatGPT ads run at $1 billion a year. It has also opened self-serve buying in seven Asian markets.

Accuracast counted 20 clicks where ChatGPT reported 100

Agencies told Digiday that the numbers do not always match. Accuracast saw 100 clicks in ChatGPT’s report but tracked only 20 on its client’s site. Form fills reported by the platform showed zero conversions two weeks later. Conversion data arrives after 24 to 36 hours, against a few hours on Google.

Agencies also miss demographic data, prompt data, independent verification and real-time attribution. Farhad Divecha, Accuracast’s chief executive, said inventory “isn’t predictable”. OpenAI declined to comment.

One agency client spends $10m a month on Google and under $100,000 on ChatGPT

One agency told Digiday that a client spends $10m a month on Google and less than $100,000 on ChatGPT. Test budgets quoted by agencies range from £10,000 to £20,000, and they want to grow them to about £100,000. Monica Shukla of Mile Marker advises setting up independent measurement before a test, not after.

Anyone running a ChatGPT test can make that check today. Put the clicks from the ChatGPT ads report next to the sessions your own analytics recorded from the same campaign, and see how far apart they are.