GPT-5.4
83% professional-level accuracy. Strong structure. Half the cost of Opus.
OpenAI's flagship released March 2026. Matches or exceeds industry professionals in 83% of comparisons across 44 occupations. 33% fewer factual errors than its predecessor. Automatic reasoning router applies the right depth of thinking without manual mode switching. Strong at structured professional output.
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How it works
Describe your brief
Type what you need: a proposal, case study, specification, or creative copy.
Choose model and document type
Pick your writing model and document length. See the credit cost before you generate.
Draft generated in seconds
Your document is drafted and ready to review, edit, copy, or export. Iterate or switch models.
Ready to draft with GPT-5.4?
Jump into the Studio and start writing. Plans from £10/month.
Choose a PlanProfessional-grade AI writing with automatic reasoning.
GPT-5.4 is OpenAI's most capable model, released March 2026. In head-to-head comparisons across 44 professional occupations, it matches or exceeds the output of human professionals 83% of the time. For design professionals drafting technical documents, tender responses, and specifications, that benchmark translates directly into usable, accurate output.
The automatic reasoning router is the headline feature. Previous models required manual mode selection (fast, balanced, deep thinking). GPT-5.4 detects the complexity of your request and applies the appropriate reasoning depth automatically. A quick email draft gets fast processing. A detailed tender document gets deep, structured reasoning. You do not need to think about which mode to use.
With 33% fewer factual errors than its predecessor and strong performance on structured professional output, GPT-5.4 sits in the sweet spot between Opus (deeper but slower and more expensive) and the mini models (faster but less capable). For most structured professional documents, it delivers excellent results at a competitive price.
Automatic reasoning depth
GPT-5.4 analyses the complexity of your request before it starts writing. Simple tasks get fast responses. Complex multi-part documents trigger deeper reasoning chains. You get the right level of thinking without manually switching modes or paying for depth you do not need.
Structured professional output
Tender documents, technical specifications, design and access statements, and project timelines all benefit from GPT-5.4's strength in structured output. It understands professional document formats and produces content that follows the conventions of each document type.
When to choose GPT-5.4
Choose GPT-5.4 for structured, formal documents where accuracy and professional formatting matter. Choose Claude Sonnet for more natural, flowing prose. Choose Opus when the document requires extensive cross-referencing across multiple source materials. GPT-5.4 is the balanced choice for most professional writing.
Questions about GPT-5.4.
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