GPT-5.5

Best for

Coding, deep reasoning, and agent workflows

Superseded by

GPT-5.6 Sol

• Context window

  1,050,000 tokens

  ≈ 788,000 words · about 3,150 pages

• Max output

  128,000 tokens

  ≈ 96,000 words in a single answer

• Knowledge cutoff

  December 2025

  its training cutoff

Modalities

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

Reasoning effort

Default: Medium.

• None

• Low

• Medium

• High

• X-High

Features

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

Tools

• Web searchSupported
• File searchSupported
• Image generationSupported
• Code interpreterSupported
• Hosted shellSupported
• Apply patchSupported
• SkillsSupported
• Computer useSupported
• MCPSupported
• Tool searchSupported