GPT-6.1 Sol

OpenAI introduced GPT-6.1 Sol on September 29, 2026, as an upgrade to GPT-6 Sol positioned as "near-Astra intelligence" at roughly one-fifth of GPT-6 Astra's standard input and output token prices. Cached input is priced at $0.10 per million tokens, described as 95% less than standard input pricing and 50% less than GPT-6 Sol's cached input pricing, giving developers more room to build agents that reuse context across requests. On DeepSWE v1.1, GPT-6.1 Sol matches GPT-6 Astra at roughly one-fifth the cost while eclipsing GPT-6 Sol's best score by 6.4 percentage points at lower reasoning effort. On GDP.pdf it exceeds Opus 5.5 with fallbacks at under half the cost per task, approaching GPT-6 Astra's performance at roughly one-fifth the cost, and on AutomationBench it scores 2.2 points above Opus 5.5 at medium reasoning effort at about a third of the cost.