ChatGPT just got another brain boost with GPT-5.4 Thinking — and it’s built for bigger, more complex tasks

• OpenAI has introduced ChatGPT 5.4 Thinking in ChatGPT to handle more complex reasoning and multi-step tasks
• ChatGPT 5.3 Instant will remain the default model for everyday conversations in ChatGPT
• The new model allows Plus, Team, and Pro users to guide the AI as it plans and completes larger projects

Barely a few days after OpenAI introduced ChatGPT 5.3 Instant, ChatGPT has received an additional upgrade called ChatGPT 5.4 Thinking, powered by the new GPT-5.4 model. ChatGPT 5.4 Thinking, along with a higher-performance ChatGPT 5.4 Pro are rolling out for the "Thinking" tool, while ChatGPT 5.3 Instant remains the default model powering most ChatGPT conversations.

The most important detail is how the new model fits into ChatGPT’s structure. ChatGPT 5.3 is basically the version optimized for speed and conversational flow, while ChatGPT 5.4 Thinking is designed for ...