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GPT-5.6
OpenAI · GPT-5
OpenAI released GPT-5.6 on July 9, 2026.
GPT-5.6 is the OpenAI model family released on July 9, 2026 in three sizes: GPT-5.6 Sol for frontier capability, GPT-5.6 Terra for a balance of intelligence and cost, and GPT-5.6 Luna for efficient, high-volume workloads. The gpt-5.6 alias routes to gpt-5.6-sol. The family is available in the Responses, Chat Completions and Batch APIs. GPT-6 later kept the Sol and Luna names, and GPT-5.6 Sol was the model other labs, including xAI, compared against in their summer 2026 benchmark tables.
GPT-5.6 at a glance
- Released
- API model id
gpt-5.6gpt-5.6-solgpt-5.6-terragpt-5.6-luna- Available on
- OpenAI API
- Previous model
- GPT-5.5 (April 24, 2026)
- Announcement
- developers.openai.com
What changed from GPT-5.5
New with GPT-5.6: Programmatic Tool Calling, explicit prompt caching controls, persisted reasoning, a max reasoning effort level, Pro mode, and Multi-agent orchestration in beta for the Responses API.
It also accepts images at their original dimensions with original or auto image detail.
New to model names and version numbers? Read how AI labs version their models.
GPT-5.6 release timeline
The launch and every later OpenAI release that mentions GPT-5.6, oldest first.
- GPT-5.6 model family
Released the GPT-5.6 model family, including GPT-5.6 Sol for frontier capability, GPT-5.6 Terra for a balance of intelligence and cost, and GPT-5.6 Luna for efficient, high-volume workloads. GPT-5.6 adds Programmatic Tool Calling, explicit prompt caching controls, persisted reas…
Source: OpenAI API Changelog - Fast mode in the API and GPT-5.6 price cuts
Starting July 30, GPT-5.6 Luna costs 80% less and GPT-5.6 Terra costs 20% less. Fast mode replaces Priority Processing in the API, delivering up to 2.5x faster speeds for GPT-5.6 Sol at twice the price; requests tagged priority automatically use Fast mode.
Source: OpenAI API Changelog - Fast mode supports long-context requests
Fast mode supports long-context requests for GPT-5.6 Sol, GPT-5.6 Terra, and GPT-5.6 Luna with 2.5× faster speeds than Standard tier.
Source: OpenAI API Changelog - chat-latest snapshot update
Updated the chat-latest snapshot, which points to the latest model available in ChatGPT for Plus and Pro users. We recommend leveraging GPT-5.6 Sol for production API usage, but feel free to use this model to test the latest improvements for chat use cases. The underlying model…
Source: OpenAI API Changelog - Ultrafast mode for GPT-5.6 Sol (limited preview)
Announced Ultrafast mode, a new API service tier for GPT-5.6 Sol that runs up to 14x faster than Standard processing. Available in limited preview to select customers.
Source: OpenAI API Changelog - GPT-5.6 Sol price cut
GPT-5.6 Sol now costs $4 per million input tokens and $20 per million output tokens, 20% lower input and 33% lower output pricing. The promotional pricing is available at least through November 21, 2026.
Source: OpenAI API Changelog - Prompt Cache Diagnostics generally available
Prompt Cache Diagnostics is now generally available in the Responses API for GPT-5.6 and later supported models. Compare cache reuse against a previous response, identify reasons for cache misses, and follow troubleshooting guidance to improve cache reuse.
Source: OpenAI API Changelog - GPT-6 Sol and GPT-6 Luna in Codex and ChatGPT Work
GPT-6 Sol and GPT-6 Luna are rolling out to Codex and ChatGPT Work at lower token prices than their GPT-5.6 predecessors. Use Sol for complex coding and agentic workflows, and Luna for focused, high-volume tasks. Select with /model or codex --model gpt-6-sol / gpt-6-luna.
Source: Codex Changelog
GPT-5.6 FAQ
When was GPT-5.6 released?
OpenAI released GPT-5.6 on July 9, 2026. The launch entry below links to the official announcement.
Where is GPT-5.6 available?
GPT-5.6 is available on OpenAI API. Later availability changes are listed under follow-up releases on this page.
What is the GPT-5.6 API model id?
Use gpt-5.6, gpt-5.6-sol, gpt-5.6-terra and gpt-5.6-luna in OpenAI's API.
What came before GPT-5.6?
GPT-5.6 follows GPT-5.5, released on April 24, 2026.
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