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GPT-5.6 Sol

OpenAI · GPT-5.6

OpenAI's flagship GPT-5.6 model for complex coding, professional work, science, design, and tool-heavy agents.

Part of GPT family · Other versions: GPT-5.6 Luna , GPT-5.6 Terra , GPT-5.5 Pro , GPT-5.5 , GPT-Rosalind , GPT-5.4 mini , GPT-5.4 nano , GPT-5.4 Pro , GPT-5.4 , GPT-5.3 , GPT-5.3-Codex , GPT-5.2-Codex , GPT-5.2 Pro , GPT-5.2 , GPT-5-Codex , GPT-5 mini , GPT-5 nano , GPT-5 , GPT-4.1 , GPT-4o mini Transcribe , GPT-4o mini TTS , GPT-4o Transcribe , Computer Use Preview , GPT-4o mini , GPT-4o
Type
language
Context
1M tokens
Max Output
128K tokens
Status
current
Input
$5/1M tok
Output
$30/1M tok
API Access
Yes
License
proprietary
frontier reasoning coding agentic tool-use computer-use long-context professional-workflows
Released July 2026 · Updated July 10, 2026

Overview

Freshness note: Model capabilities, limits, pricing, and availability can change quickly. This profile is a point-in-time snapshot last verified on July 10, 2026.

GPT-5.6 Sol is OpenAI’s flagship GPT-5.6 model for complex professional work. OpenAI moved the family from a limited trusted-partner preview to general availability on July 9, 2026 across standard ChatGPT reasoning on eligible paid plans, ChatGPT Work, Codex, and the API. The model sits above GPT-5.6 Terra and GPT-5.6 Luna when the workflow needs the highest capability ceiling rather than the lowest per-request cost.

For API callers, the exact model ID is gpt-5.6-sol. The shorter gpt-5.6 alias also routes to Sol, making this the family default for new frontier deployments.

Capabilities

Sol is designed for agentic coding, research, cybersecurity, scientific work, computer use, design, and document-heavy knowledge workflows. OpenAI emphasizes better persistence, stronger intent understanding, improved frontend and visual judgment, and more efficient use of output tokens than GPT-5.5.

The GPT-5.6 API generation also adds Programmatic Tool Calling for bounded tool-heavy workflows, persisted reasoning across turns, explicit prompt-cache breakpoints, and a multi-agent beta for parallel workstreams. Sol supports reasoning efforts from none through max; teams should benchmark lower settings before defaulting to the most expensive mode.

Technical Details

OpenAI’s API docs list:

  • Model ID: gpt-5.6-sol
  • Alias: gpt-5.6
  • Context window: 1,050,000 tokens
  • Maximum output: 128,000 tokens
  • Knowledge cutoff: February 16, 2026
  • Input: text and images
  • Output: text

Streaming, function calling, and structured outputs are supported. The documented Responses tool surface includes web and file search, image generation, code interpreter, hosted shell, apply patch, skills, computer use, MCP, and tool search. Fine-tuning is not currently supported.

OpenAI also exposes reasoning.mode: "pro" on the selected GPT-5.6 model. This is a mode, not a separate gpt-5.6-sol-pro API slug.

Pricing & Access

Published standard API pricing per 1M tokens is:

  • Input: $5.00
  • Cached input: $0.50
  • Output: $30.00

Prompts above 272K input tokens are billed at 2x input and 1.5x output for the full request. GPT-5.6 cache writes cost 1.25x the uncached input rate, while cache reads receive the documented cached-input discount.

In standard ChatGPT conversations, Sol powers the Medium, High, and Extra High reasoning options on eligible paid plans, while Sol Pro powers Pro. Sol, Terra, and Luna are also available through ChatGPT Work, Codex, and the OpenAI API with product- and plan-specific boundaries. Access remains subject to workspace, region, and rollout controls, and product-level options such as Sol Pro and ultra do not map one-to-one to separate API model pages.

Best Use Cases

Choose Sol for difficult repository work, long-horizon debugging, architecture analysis, high-quality document and presentation creation, scientific research support, defensive security work, and tool-using agents where failed attempts are more expensive than the model premium.

Do not use it as the automatic default for routine extraction, classification, or high-volume drafting. Terra and Luna preserve the GPT-5.6 feature generation at lower prices and may match the required quality with less spend.

Comparisons

  • GPT-5.6 Terra (OpenAI): Better balance of intelligence and cost for broad production use.
  • GPT-5.6 Luna (OpenAI): Lowest-cost GPT-5.6 route for high-volume and supporting workloads.
  • GPT-5.5 (OpenAI): Still documented and available, but no longer OpenAI’s newest frontier generation.
  • Claude Fable 5 (Anthropic): Premium competing model for difficult agentic and professional work.