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openai/gpt-5-1
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GPT-5.1

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

11/13/2025
400,000 tokens

Specifications

Modalities

Input
image
text
file
Output
text

Supported Parameters

include_reasoning
max_tokens
reasoning
response_format
seed
structured_outputs
tool_choice
tools

Max Output Tokens

128,000

Reasoning Configuration

Default
Thinking on (effort: none)
Selectable effort levels
high
medium
low
none
Turning thinking off
Possible (reasoning.enabled: false)

How to control thinking, and what it costs

Frequently asked questions

Is GPT-5.1 available on FastMetal?
Not at the moment. GPT-5.6 Sol, from the same lab, is available on the FastMetal API today.
What is the context window of GPT-5.1?
400,000 tokens, shared between the prompt and the response.