Introducing GPT‑5.4

Simon Willison’s Weblog Subscribe Sponsored by: CodeRabbit — Planner helps 10x your coding agents while minimizing rework and AI slop. Try Now. Introducing GPT‑5.4. Two new API models: gpt-5.4 and gpt-5.4-pro, also available in ChatGPT and Codex CLI. August 31st 2025 knowledge cutoff, 1 million token context window. Priced slightly higher than the GPT-5.2 family with a bump in price for both models if you go above 272,000 tokens. 5.4 beats coding specialist GPT-5.3-Codex on all of the relevant benchmarks. I wonder if we'll get a 5.4 Codex or if that model line has now been merged into main? Given Claude's recent focus on business applications it's interesting to see OpenAI highlight this in their announcement of GPT-5.4: We put a particular focus on improving GPT‑5.4’s ability to create and edit spreadsheets, presentations, and documents. On an internal benchmark of spreadsheet modeling tasks that a junior investment banking analyst might do, GPT‑5.4 achieves a mean score of 87.3%, compared to 68.4% for GPT‑5.2. Here's a pelican on a bicycle drawn by GPT-5.4: And here's one by GPT-5.4 Pro, which took 4m45s and cost me $1.55: Posted 5th March 2026 at 11:56 pm Recent articles My fireside chat about agentic engineering at the Pragmatic Summit - 14th March 2026 Perhaps not Boring Technology after all - 9th March 2026 Can coding agents relicense open source through a “clean room” implementation of code? - 5th March 2026 This is a link post by Simon Willison, posted on 5th March 2026. ai 1913 openai 401 generative-ai 1696 llms 1662 pelican-riding-a-bicycle 100 llm-release 184 Monthly briefing Sponsor me for $10/month and get a curated email digest of the month's most important LLM developments. Pay me to send you less! Sponsor & subscribe Disclosures Colophon © 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026