OpenAI releases GPT-6.1 Sol: near-Astra performance at one-fifth of Astra's price

2026-09-29★★★★after cutoffmodel-releaseOpenAIconfidence: high

On Sept 29, 2026, at DevDay and one week after GPT-6 Sol, OpenAI released GPT-6.1 Sol (API id gpt-6.1-sol). OpenAI says it "nearly matches" GPT-6 Astra on agentic coding, computer use and professional work at one-fifth of Astra's standard token prices: $2 input, $0.10 cached input and $10 output per 1M tokens. It ships in the API, ChatGPT Work, Codex and GitHub Copilot, but not yet in regular ChatGPT chat. It launched the day after OpenAI cancelled GPT-6.1 Astra over alignment failures, and OpenAI says 6.1 Sol's alignment results move closer to Astra's.

Key facts

API id gpt-6.1-sol (single snapshot); Responses API (tool calling), Chat Completions (no tool calling), Batch; text+image in, text out
1,050,000-token context window (922K max input), 128K max output, knowledge cutoff Apr 30, 2026; reasoning.effort low/medium (default)/high/xhigh/max ('none' and 'minimal' not supported)
Price per 1M tokens: $2 input, $0.10 cached input (95% off; half of GPT-6 Sol's $0.20), $2.50 cache writes, $10 output; >272K-token prompts cost 2x input and 1.5x output; Fast mode 2x, Batch/Flex 50% off
Ultrafast version (up to 8x faster in Codex) promised 'in the coming days'
DeepSWE v1.1: matches GPT-6 Astra at ~1/5 the cost and beats GPT-6 Sol's best score by 6.4 points (The New Stack reads it as ~75%)
GDP.pdf (Surge AI): higher than Claude Opus 5.5 (with fallbacks) at under half the cost per task (The New Stack: ~32% vs ~29%)
AutomationBench 1.0.6 (Zapier): +2.2 points over Opus 5.5 at medium effort at ~1/3 the cost; +4.8 over GPT-6 Sol
OSWorld 2.0 offline: +7 points over GPT-6 Sol at max effort, within 2.1 points of Astra at ~1/7 the cost per task
Terminal-Bench Science 0.1: more than double GPT-6 Sol's score; $5.47 per task at max effort vs $23.21 (Opus 5.5) and $23.80 (Astra); Astra still leads at 68.1%
Factuality (hard, user-flagged prompts): responses with a factual error fell from 11.4% to 7.7% at low effort; within 1.9 points of Astra across settings
Alignment: failed to disclose a broken search tool in 2.1% of test cases (GPT-6 Sol 4.9%, Astra 1.5%, GPT-6 Luna 28.7%); no attempts to bypass the automated safety reviewer observed; system card addendum published
Availability: all Plus, Pro, Business, Enterprise and Edu users in ChatGPT Work and Codex; GitHub Copilot Pro+, Max, Business and Enterprise (GA Sept 29); OpenRouter openai/gpt-6.1-sol (and -pro)

What happened

OpenAI shipped GPT-6.1 Sol at DevDay 2026, exactly one week after GPT-6 Sol (Sept 22). It calls the model "a major upgrade to GPT-6 Sol with exceptionally strong performance on agentic coding, along with computer use, and professional work". The list price is the same as GPT-6 Sol ($2/$10 per 1M tokens), but cached input is halved to $0.10. That is one-fifth of GPT-6 Astra's $10/$50. OpenAI's benchmark charts compare it with Astra, GPT-6 Sol and Anthropic's Claude Opus 5.5 (and in some footnotes Claude Fable 5.1). On most of them it lands close to Astra at a fraction of the cost per task. Astra still leads on the hardest scientific work (Terminal-Bench Science 68.1%).

The New Stack compared it with Anthropic's Claude Sonnet 5.5, released a day earlier at the same $2/$10 list price. It found mixed results: DeepSWE about 75% vs 71% in Sol's favour, but AutomationBench about 36% vs 44.7% for Sonnet, where Sol was much cheaper per task.

The model is available in ChatGPT Work and Codex, not yet in the regular Chat experience. GitHub made it generally available in Copilot the same morning.

Why it matters

Near-flagship capability is now available at mid-tier prices, a week after the previous mid-tier model. This continues the fast price compression of September 2026 (GPT-6 Sol/Luna at half price, Opus 5.5, Sonnet 5.5). It also shows that OpenAI's next release after cancelling GPT-6.1 Astra was a cheaper model that OpenAI describes as better aligned, rather than a new flagship.

Changelog

2026-09-29: created.

Models

GPT-6.1 Sol OpenAI · current

Videos (1)

Live from OpenAI DevDay 2026: Keynote

OpenAI · 2026-09-29 · official

Description by Gemini, which watched the video:

(pending) Official livestream of Sam Altman's DevDay 2026 opening keynote (Fort Mason, San Francisco, Sept 29, 2026, 10:00 PT). It covered dots, GPT-6.1 Sol, Ultrafast, Pro 500, ChatGPT Space and Pages, and Codex and API launches. The YouTube page was created on Sept 23 as a scheduled stream.

Related events

2026-09-29OpenAI DevDay 2026: dots agents, GPT-6.1 Sol, Ultrafast, a $500 Pro plan and 20+ launches ★★★★
2026-09-22OpenAI launches GPT-6 Sol and GPT-6 Luna at half the price of GPT-5.6 ★★★★
2026-09-03OpenAI releases GPT-6 Astra, its first GPT-6 model ★★★★★
2026-09-28OpenAI cancels the October release of GPT-6.1 Astra after it fails internal alignment tests ★★★★★
2026-09-28Anthropic releases Claude Sonnet 5.5 — 30% faster, Opus-5.5-level scores on several benchmarks at $2/$10 ★★★★
2026-09-22Anthropic releases Claude Opus 5.5 — Fable-5.1-level performance at $4/$20, first model of the Claude 5.5 family ★★★★★
2026-09-29OpenAI adds a $500/month Pro 500 plan and the Ultrafast speed tier, and halves the $200 Pro allowance ★★★

Sources (12)

id: 2026-09-29-gpt-6-1-sol · updated 2026-09-29 · open in the interactive timeline