OpenAI: gpt-5.1

gpt-5.1
400K context128K outReasoningToolsParallel toolsVisionFilesCacheStructuredStreamingSystem msg
Released Nov 13, 2025Knowledge cutoff 2024Updated Nov 13, 2025

GPT-5.1 is the latest frontier-grade model in the GPT-5 series, offering stronger general-purpose reasoning, improved instruction adherence, and a more natural conversational style compared to GPT-5. It uses adaptive reasoning to allocate computation dynamically, responding quickly to simple queries while spending more depth on complex tasks. The model produces clearer, more grounded explanations with reduced jargon, making it easier to follow even on technical or multi-step problems. Built for broad task coverage, GPT-5.1 delivers consistent gains across math, coding, and structured analysis workloads, with more coherent long-form answers and improved tool-use reliability. It also features refined conversational alignment, enabling warmer, more intuitive responses without compromising precision. GPT-5.1 serves as the primary full-capability successor to GPT-5

Mode chatTokenizer GPTReasoning levels none, low, medium, high, max

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Pricing

Input price
$0.75/ 1M tokens$1.2540% off
Output price
$6.00/ 1M tokens$10.0040% off
Context window 400K tokensCompatible endpoints openai, openai-response, anthropicVendor OpenAI

Performance

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Usage & Ranking

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Supported parameters

All providers = every upstream serving this model supports it. Some providers = depends on which upstream handles the request. Default = the value sent when you leave the parameter unset.

ParameterProvidersDefault
frequency_penaltySome providersNot sent by default
include_reasoningAll providers-
max_completion_tokensSome providers-
max_tokensSome providers-
presence_penaltySome providersNot sent by default
reasoningAll providers-
repetition_penaltySome providersNot sent by default
response_formatAll providers-
seedAll providers-
structured_outputsAll providers-
temperatureSome providersNot sent by default
tool_choiceAll providers-
toolsAll providers-
top_kSome providersNot sent by default
top_pSome providersNot sent by default

Frequently asked questions

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