GPT-5.1 Thinking

openai

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. OpenAI's flagship language model that excels at complex reasoning, broad real-world knowledge, code-intensive, and multi-step agentic tasks.

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Capabilities

Tool Use

Image Input

File Input

Extended Thinking

Technical Specifications

Context Window

400,000 tokens

Max Output

128,000 tokens

Confidence Scale

2.7x (above average)

Input Cost

$1.25 per 1M tokens

Output Cost

$10 per 1M tokens

File Input Limit

20 files

Files in Assistant Messages

Yes

Availability

Free

Minimum plan required

$0 per month

Also available in these plans

Plus
$20/mo
Pro
$100/mo
Super
$200/mo