What is the context window size of GPT-5.4?

GPT-5.4 API supports up to 922,000 input + 128,000 output tokens (over 1M total), enabling full codebase processing in one session with 33% fewer hallucinations and 18% fewer factual errors versus prior models.

How does GPT-5.4 differ from GPT-5.3?

GPT-5.4 unifies Codex capabilities, adds autonomous agentic workflows with mid-task steering, native Excel integration, and reduces hallucinations by 33%—a leap from chatbot to autonomous work agent.

What can ChatGPT for Excel do?

Generate dynamic arrays and trigger data analysis in Excel cells via natural language, plus cross-software automation covering file operations, code execution, and online data validation in a single workflow.

— AI DAILY

Sources

OpenAI Official Blog
TechCrunch
The Verge
Julian Goldie