OpenAI unveils GPT-6.1 Sol
- Maxime Hiez
- OpenAI
- 02 Oct, 2026
Introduction
OpenAI announced, at DevDay 2026 on September 29, 2026, GPT-6.1 Sol, an improved version of GPT-6 Sol that closes the gap with GPT-6 Astra on agentic coding, computer use, and professional work, at a fifth of Astra’s standard rates. The model replaces GPT-6 Sol just seven days after that model’s launch, the shortest replacement cycle OpenAI has ever executed.
See the article on GPT-6 Astra HERE.
Coding
On DeepSWE v1.1, which evaluates complex software engineering tasks in real codebases, GPT-6.1 Sol matches GPT-6 Astra for about a fifth of the cost, while beating GPT-6 Sol’s best score by 6.4 percentage points, at lower reasoning effort and cost.
Professional work
On GDP.pdf, which measures answer accuracy on professional questions drawn from complex PDFs (tables, charts, fine print), GPT-6.1 Sol beats Claude Opus 5.5 at less than half the cost per task, across every reasoning setting tested, and approaches GPT-6 Astra’s reference performance for about a fifth of the cost per task.
On AutomationBench, which tests end-to-end business workflows across 47 tools (sales, marketing, operations, support, finance, HR), GPT-6.1 Sol beats Opus 5.5 by 2.2 percentage points at medium effort, for about a third of the cost, and beats GPT-6 Sol by 4.8 points at the same setting.
Computer use
On the offline split of OSWorld 2.0, GPT-6.1 Sol beats GPT-6 Sol by 7 percentage points at maximum reasoning effort, at less than half the cost, and lands within 2.1 points of GPT-6 Astra’s score for about a seventh of the cost per task.
Scientific research
On Terminal-Bench Science 0.1, GPT-6.1 Sol more than doubles GPT-6 Sol’s score at maximum effort, at less than half the cost per task. At that setting, GPT-6.1 Sol costs an average of 5.47$ per task, compared with 23.21$ for Opus 5.5 and 23.80$ for GPT-6 Astra, a cost more than 75% lower than either model. GPT-6 Astra still leads with a score of 68.1%, however, and remains the recommended choice for the most demanding scientific research tasks.
Factual accuracy and alignment
At very high reasoning effort, GPT-6.1 Sol’s factual error rate stands at 4.1%, compared with 4.5% for GPT-6 Sol and 4.0% for GPT-6 Astra, at about 83% lower cost per task than Astra.
| GPT-6.1 Sol | GPT-6 Sol | GPT-6 Astra | |
|---|---|---|---|
| Factual error rate | 4.1% | 4.5% | 4.0% |
On alignment evaluations, GPT-6.1 Sol reduces failure rates compared with GPT-6 Sol on transparency about failing research tools, adherence to explicit restrictions, and prevention of unauthorized outcomes in agentic contexts. OpenAI observed no attempts to circumvent an automated safety control system, as with GPT-6 Sol and GPT-6 Astra.
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Pricing and availability
GPT-6.1 Sol is available starting September 29, 2026 to all Plus, Pro, Business, Enterprise, and Edu users in ChatGPT Work and Codex. The model is not yet available in Chat. Developers can access it through the OpenAI API under the identifier gpt-6.1-sol :
- Input : 2$ / 1M tokens
- Cached input : 0.10$ / 1M tokens (95% below standard input pricing)
- Output : 10$ / 1M tokens
OpenAI is launching GPT-6 Astra Ultrafast alongside it, up to 8x faster than GPT-6 Astra, as well as GPT-6.1 Sol Ultrafast. Both variants are available in the API as well as in ChatGPT Work and Codex for users on the new Pro tier at 500$/month, which offers the highest usage limits. GPT-6.1 Sol Ultrafast delivers near-Astra intelligence up to 8x faster, at an API cost close to what GPT-6 Astra alone previously cost.
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Conclusion
GPT-6.1 Sol shifts the performance-to-cost balance in the OpenAI lineup : it approaches GPT-6 Astra on several demanding tasks while staying at Sol’s price point, making it the best price-performance model currently on offer. GPT-6 Astra still holds the top absolute score on the hardest scientific and cybersecurity tasks, however, and remains the recommended choice when performance matters more than cost.
Sources
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