GPT-6.1 Sol (`gpt-6.1-sol`): launched at DevDay on 2026-09-29, 1,050,000-token context window (max input 922,000, max output 128,000, same as GPT-6 Sol); standard pricing unchanged at $2.00 input / $10.00 output, but cached input is halved again from GPT-6 Sol's $0.20 to $0.10 (95% below standard input); matches GPT-6 Astra on DeepSWE v1.1 at roughly 1/5 of Astra's cost, beating GPT-6 Sol's best score by 6.4 points; beats Claude Opus 5.5 on AutomationBench at medium effort by 2.2 points at about 1/3 the cost; in the same week OpenAI shelved a flagship upgrade, GPT-6.1 Astra, over safety concerns and did not release it
GPT-6 Sol (`gpt-6-sol`) / GPT-6 Luna (`gpt-6-luna`) shipped 2026-09-22; 1,050,000-token context window (922,000-token max input, 128,000-token output cap — same as flagship Astra); Sol prices at $2.00 input / $10.00 output, Luna at $0.10 input / $0.50 output per 1M tokens (a further 50% cut versus GPT-5.6 promotional pricing); Sol hits 33.2% on AutomationBench at xhigh effort, beating Claude Opus 5's 26.9% at roughly 1/11 the cost; DeepSWE v1.1 puts Sol at 68.8% and Luna at 66.6%, closing in on Claude Fable 5.1's 69.9%; in OpenAI's internal simulated deployment testing, severity-3+ misalignment flags dropped from 66 to 42 versus the prior generation
GPT-6 Astra (API ID: gpt-6-astra): released by OpenAI on 2026-09-03, 1,050,000-token context window, 128,000 max output tokens, input $10.00 / output $50.00 per 1M tokens (cached input $1.00), closed-source; 99.9% on ARC-AGI-3 under OpenAI's own harness (62.7% on the standardized harness), 97.6% on FrontierMath Tier 4, 100% on ExploitBench; the first model rated 'Critical' cybersecurity capability under OpenAI's Preparedness Framework; yet scores only 61 on the neutral Artificial Analysis Intelligence Index — tied with predecessor GPT-5.6 Sol and behind Claude Fable 5.1's 66
GPT is OpenAI's LLM family, from 117M parameters in 2018 to the three-tier GPT-5.6 Sol/Terra/Luna lineup in 2026, serving 1B+ users and 2M enterprise customers. GPT-5.6 Sol leads LiveBench 81.1%, Terminal-Bench 2.1 88.8%, and Artificial Analysis Coding Agent Index 80 across multiple agentic benchmarks, while OpenAI's first open-weight model GPT-OSS ships under Apache 2.0.