GPT-6.1 Sol charges less than GPT-6 Sol for cached input
GPT-6.1 Sol (gpt-6.1-sol) is a model OpenAI released on 29 September 2026[1]. It is aimed at complex coding, computer use and professional work, and OpenAI says it delivers near-Astra performance at a lower cost than GPT-6 Astra[1,2].
Per million tokens it costs $2 input, $0.10 cached input, $2.50 for cache writes and $10 output[1,2]. Compared with GPT-6 Sol, released on 22 September, input and output are unchanged and cached input is half of its $0.20[1].
For requests with more than 272K input tokens, the full request is billed at twice the input and cache rates and 1.5 times the output rate[2]. That comes to $4 input and $15 output per million tokens[2].
Fast mode costs twice the standard rates, Batch and Flex half, and choosing regional processing adds 10 percent[2].
Ultrafast mode, available on GPT-6 Astra since 29 September, came to GPT-6.1 Sol on 8 October[1]. Setting service_tier to ultrafast in the Responses API shortens the time between generated output tokens[1,2].
Ultrafast costs six times the standard rates, which is $12 input and $60 output per million tokens[2].
One request can use a context of 1,050,000 tokens and up to 128,000 output tokens, and the knowledge cutoff is 30 April 2026[2].
reasoning.effort takes one of five values, low, medium, high, xhigh and max, with medium as the default[2]. none and minimal are not supported[2]. Tool calling works only in the Responses API, and Chat Completions is supported without tools[2].
Multi-agent is supported in beta, so the model can delegate work to subagents within one Responses API request[1].
On 6 October OpenAI consolidated its API usage tiers from five into three: Build, Launch and Grow[1].
Per minute, GPT-6.1 Sol is limited to 5,000 requests and 1 million tokens on Build, 10,000 requests and 4 million tokens on Launch, and 15,000 requests and 40 million tokens on Grow[2]. It is not available on the free tier[2].