GPT-6.1 Sol replaces GPT-6 Sol after just 7 days, with near-Astra intelligence (artificialanalysis.ai)

On September 29, 2026, OpenAI announced the rapid deployment of GPT-6.1 Sol, which replaces its predecessor GPT-6 Sol after just one week. Notably, GPT-6.1 Sol scores only one point below the highly regarded GPT-6 Astra in the Intelligence Index while delivering significant cost efficiency—less than a quarter of the cost per task compared to Astra. This new model matches the pricing structure of GPT-6 Sol but increases cache read discounts from 90% to 95%, enhancing its appeal for agentic workloads with a blended price lower than its predecessor. The significance of GPT-6.1 Sol lies in its impressive intelligence advancements, achieving noteworthy gains across multiple benchmarks: 4 to 12 points across key assessments like AA-Briefcase and GDPval-AA. It also excels in coding tasks, outperforming GPT-6 Astra at a fraction of the cost and achieving a reduction in hallucination rates from 60% to 54%. Although GPT-6.1 Sol requires 10-30% more output tokens than GPT-6 Sol, its enhanced intelligence metrics at low and medium effort levels make it a standout option in terms of token efficiency, setting a new standard in the AI/ML landscape for both performance and affordability.