Model Release Notes | OpenAI Help Center

Model Release Notes<br>Updated: 3 hours ago<br>GPT-5.5 Instant Update (May 28, 2026)<br>We’re updating GPT-5.5 Instant in ChatGPT and the API to improve response style and quality. It’s now easier to read, more natural in everyday conversations, and better paced in practical help tasks, with fewer overly long or bullet-heavy responses.

With this update, canvas will no longer be available in GPT-5.5 Instant or GPT-5.5 Thinking. Writing and coding functionality is now supported directly in chat responses through writing blocks and code blocks. Paid users can continue using canvas for a limited time through legacy models until those models are sunset.<br>Retiring OpenAI o3 and GPT-4.5 (May 28, 2026)<br>Today, we’re continuing to retire older models with limited usage in ChatGPT so we can better serve our newer, most capable models. OpenAI o3 will be retired from ChatGPT on August 26, 2026 following a 90-day sunset period, and GPT-4.5 will be retired from ChatGPT on June 27, 2026 following a 30-day sunset period. These models are currently available to paid users only via model settings. These changes apply to ChatGPT only; there are no changes to the API.

GPT-5.4 mini in ChatGPT (March 18, 2026)<br>We’re rolling out GPT-5.4 mini in ChatGPT. GPT-5.4 mini is available to Free and Go users via the “Thinking” feature in the + menu. For all other users, GPT-5.4 mini is available as a rate limit fallback for GPT-5.4 Thinking.

For Plus, Pro, and other paid users, GPT-5.4 mini will be used as a fallback for GPT-5.4 Thinking when rate limits are reached, helping with continued access to reasoning capabilities during high usage. Enterprise customers will retain the option to default Auto routing to GPT-5.4 mini, if preferred.

GPT-5.4 mini will not appear as a selectable model in the model picker, and GPT-5 Thinking mini will be retired as a selectable option in 30 days. Learn more in our blog post.

GPT-5.3 Instant update (March 16, 2026)<br>We’re rolling out an update to GPT-5.3 Instant that improves follow-up tone and reduces teaser-style phrasing in responses (e.g., “If you want…”, “You’ll never believe…”, “I can tell you these three things that…”).

Retiring GPT-5.1 models (March 11, 2026)<br>As of March 11, 2026, GPT-5.1 models are no longer available in ChatGPT.

This applies to GPT-5.1 Instant, GPT-5.1 Thinking, and GPT-5.1 Pro. Existing conversations that used GPT-5.1 will automatically continue on the corresponding current model: GPT-5.3 Instant, GPT-5.4 Thinking, or GPT-5.4 Pro.

GPT-5.4 Thinking in ChatGPT (March 5, 2026)<br>GPT‑5.4 brings together the best of our recent advances in reasoning, coding, and agentic workflows into a single frontier model. It incorporates the industry-leading coding capabilities of GPT‑5.3‑Codex⁠ while improving how the model works across tools, software environments, and professional tasks involving spreadsheets, presentations, and documents. The result is a model that gets complex real work done accurately, effectively, and efficiently—delivering what you asked for with less back and forth.

In ChatGPT, GPT‑5.4 Thinking can now provide an upfront plan of its thinking, so you can adjust course mid-response while it’s working, and arrive at a final output that’s more closely aligned with what you need without additional turns. GPT‑5.4 Thinking improves deep web research, particularly for highly specific queries, while better maintaining context for questions that require longer thinking. GPT‑5.4 Thinking also has improved context window management that supports its ability to think for longer. Together, these improvements mean higher-quality answers that arrive faster and stay relevant to the task at hand.

GPT-5.3 Instant Update (March 3, 2026)<br>GPT‑5.3 Instant delivers more accurate answers, richer and better-contextualized results when searching the web, and reduces unnecessary dead ends, caveats, and overly declarative phrasing that can interrupt the flow of conversation.

This update focuses on the parts of the ChatGPT experience people feel every day: tone, relevance, and conversational flow. These are nuanced problems that don’t always show up in benchmarks, but shape whether ChatGPT feels helpful or frustrating. GPT‑5.3 Instant directly reflects user feedback in these areas.

Retiring GPT-4o and other legacy models (February 13, 2026)<br>As previously announced, we have retired GPT-4o, GPT-4.1, GPT-4.1 mini, and OpenAI o4-mini from ChatGPT. We are also retiring GPT-5 (Instant and Thinking), as previously announced. There are no API changes at this time. For details, see our blog post and Help Center.

GPT-5.2 Instant Update  (February 10, 2026)<br>We’re making an update to GPT-5.2 Instant in ChatGPT and the API that improves response style and quality.

Users should notice responses that are more measured and grounded in tone, in a way that’s more contextually appropriate to the conversation. The model also tends to output clearer, more relevant answers to...