OpenAI makes major upgrades for free and paid ChatGPT users

Driving the news: OpenAI said it will shift the default model for all users to GPT-5.6 Luna this week.

• OpenAI says that responses featuring at least one factual error were 62% less common with Luna opposed to the previous default model, GPT‑5.5 Instant. Luna, which debuted in early July, was built for speed.
• Unlimited text chats will be given to free users and those who subscribe to the low-cost Go plan. Both free and go users will also see a new "Think" button, which lets users "select higher reasoning for harder questions," the company says.

Plus and Pro users will see GPT-5.6 Sol improved to handle "everyday conversations and tasks, like quick questions, web research, advice, planning, writing, and decisions," OpenAI says.

• "This version of GPT-5.6 Sol delivers more focused answers," the company said, with less unnecessary formatting, a consistent tone and fewer mistakes.

• It will also feature a new "slider" tool "for choosing how much thought ChatGPT puts into an answer," OpenAI says.

The big picture: Cheaper Chinese open-weight models have increased pressure on OpenAI and Anthropic to prove their models justify the higher costs.

• OpenAI recently cut the prices for two of its GPT-5.6 models — GPT-5.6 Luna and GPT-5.6 Terra — last week.
• Price cuts have previously come months after a model launches, not weeks.

Go deeper: Finding your goldilocks GPT-5.6 model