GPT-5.5 Pro
The newest of the Pro models. Thinks for longer before answering, over very long documents; built for hard problems, not chat or code.
- Best for
- Deep reasoning
- Use instead
- 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: High.
Features
- StreamingNot supported
- Function callingSupported
- Structured outputsSupported
- Fine-tuningNot supported
Tools
- Web searchSupported
- File searchSupported
- Image generationSupported
- Code interpreterSupported
- Hosted shellSupported
- Apply patchNot supported
- SkillsNot supported
- Computer useNot supported
- MCPSupported
- Tool searchNot supported
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