GPT-5.1

Best for

Coding, deep reasoning, and agent workflows

Superseded by

GPT-5.2

• Context window

  400,000 tokens

  ≈ 300,000 words · about 1,200 pages

• Max output

  128,000 tokens

  ≈ 96,000 words in a single answer

• Knowledge cutoff

  September 2024

  its training cutoff

Modalities

• TextInput and output
• ImageInput only
• AudioNot supported
• VideoNot supported

Reasoning effort

Default: None.

• None

• Low

• Medium

• High

Features

• StreamingSupported
• Function callingSupported
• Structured outputsSupported
• Fine-tuningNot supported

Tools

• Web searchSupported
• Tool searchNot supported