ChatGPT got the lowest price wrong in most tests, Which? finds ahead of sales season

Shoppers hoping to use AI chatbots to find the cheapest deals in the upcoming sales have been warned that the technology frequently gets prices wrong, after consumer group Which? tested ChatGPT against real retailer prices.

In a survey of 1,078 members of its Which? Connect panel, carried out in September 2026, Which? found that more than half of respondents used AI chatbots at least some of the time, with 32% using them for shopping or researching purchases. Among those, 29% said they would use AI specifically to find the best deals on products.

Most results contained errors

When Which? tested ChatGPT, the most widely used chatbot among those surveyed, it correctly identified the lowest price and retailer for only eight products. In 68% of cases there was at least one problem with the result, including the wrong price listed for a retailer, missing cheaper prices available elsewhere, or prices shown for the wrong product entirely.

Which? said some results appeared to pull figures from price comparison sites that were out of date or inaccurate. In other cases, a prominent “product result” or “shopping” box shown above search results displayed the wrong model or a higher price than other listings.

Price gaps of up to £200

For a Lenovo Chromebook, Which? found the lowest price from a reputable retailer was £599. ChatGPT instead cited a figure of £399, attributing it to Which?, but this turned out to be the lowest price recorded over the previous six months rather than a current price. The chatbot’s accompanying product box also showed the wrong laptop, priced at £699 at Argos. Which?’s own research found the actual lowest current price was £499, at a different retailer.

For a Microsoft Surface Pro 12-inch laptop, ChatGPT said the lowest price it could find was £919.08 via the Microsoft Store. When Which? clicked through, the real price was £999. The actual lowest price available was £899 via Amazon, meaning a shopper relying on the chatbot’s figure could have paid £100 more than necessary.

What OpenAI said

Which? shared its findings with OpenAI, the company behind ChatGPT. It said: “ChatGPT search provides links so users can check prices directly with retailers. Prices in its initial product listings may not be the lowest available. Improving factual accuracy remains a major focus, and we’re working to update pricing information faster.”

What happens next

Which? said inaccurate chatbot results can waste shoppers’ time, for example if a requested list of budget items turns out to contain options priced above the stated limit, or cause buyers to miss genuinely cheap deals that the chatbot has wrongly flagged as more expensive. The organisation said no changes to ChatGPT’s pricing accuracy have yet been confirmed beyond OpenAI’s stated commitment to improve the speed at which pricing data is updated. Which? has published a set of sales season tips, including shopping with reputable retailers, checking delivery fees, using price comparison sites and treating AI chatbot results with caution, ahead of the main sales period.