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GPT 5.1 Thinking (Fast) – Model Docs — Person.run

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GPT 5.1 Thinking (Fast)

An upgraded version of GPT-5 that adapts thinking time more precisely to the question to spend more time on complex questions and respond more quickly to simpler tasks.

Model overview

Model ID: openai/gpt-5.1-thinking-fast
Provider: openai
Type: language
Context window: 400,000 tokens
Max output tokens: 128,000

Tags: file-input, implicit-caching, reasoning, tool-use, vision, web-search, fast

Model pricing

Metric	Value
`Input tokens (/1M)`	`$2.50`
`Output tokens (/1M)`	`$20.00`
`Image generation`	`n/a`
`Cached input read (/1M)`	`$0.25`
`Cached input write (/1M)`	`n/a`
`Pricing source`	`gateway`

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