OpenAI unveils GPT-6.1 Sol: near-Astra performance at one-fifth the price

#What happened

OpenAI introduced GPT-6.1 Sol, an upgrade to GPT-6 Sol, at its DevDay 2026 event on September 29, 2026. The model is available in the API at $2 per million input tokens and $10 per million output tokens — roughly one-fifth of GPT-6 Astra's standard token prices. Cached input costs $0.10 per million tokens, which OpenAI describes as 95% below standard input pricing and 50% below GPT-6 Sol's cached input price.

Starting September 29, 2026, GPT-6.1 Sol is available to all Plus, Pro, Business, Enterprise, and Edu users in ChatGPT Work and Codex. Developers can access it through the OpenAI API as gpt-6.1-sol. It is not yet available in Chat. An Ultrafast option with up to eight times faster token generation in Codex will follow in the coming days.

#Why it matters

On DeepSWE v1.1, OpenAI reports GPT-6.1 Sol matches GPT-6 Astra at roughly one-fifth of the cost while exceeding GPT-6 Sol's best score by 6.4 percentage points. On GDP.pdf, it scores higher than Opus 5.5 with fallbacks at less than half the cost per task. On factuality, the share of responses containing a factual error fell from 11.4% with GPT-6 Sol to 7.7% with GPT-6.1 Sol at low reasoning effort — a reduction of about 32%.

The release landed as part of more than 20 announcements in OpenAI's DevDay 2026 recap, spanning Codex developer tools, the API, ChatGPT collaboration features, plugins, and subscription plans. It arrives while GPT-6.1 Astra's launch remains on hold over internal safety-test concerns reported by the Wall Street Journal.

#Sources

• Unite.AI: https://www.unite.ai/openai-unveils-gpt-6-1-sol-at-devday-with-new-codex-and-chatgpt-tools/
• dev.to: http://dev.to/axrisi/openai-devday-2026-every-announcement-with-prices-and-availability-1mbh

Verified 2026-09-29.