OpenAI is introducing a new version of its ChatGPT deep research tool that it says is cheaper to operate. The “lightweight” model is available now to free users, as well as those on several of the company’s paid tiers.

Lightweight o4-mini activates after users hit usage limits, offering shorter but thorough answers with 45.6% accuracy compared to deep research’s 51.5%.

The tool built for creating in-depth reports in minutes is now available on all versions of ChatGPT, albeit in a new 'lightweight' form.