Claude Opus 4.5 vs GPT-5.1 Chat: side-by-side summary

Claude Opus 4.5 and GPT-5.1 Chat are available through the OpenRouter API, so switching between them takes a model slug change rather than a new integration.

Claude Opus 4.5, from Anthropic, has a 200,000-token context window and is priced at $5/M tokens input, $25/M tokens output on OpenRouter.

GPT-5.1 Chat, from OpenAI, has a 128,000-token context window and is priced by the provider serving it on OpenRouter.

Context window

• Claude Opus 4.5: 200,000 tokens
• GPT-5.1 Chat: 128,000 tokens

Price

• Claude Opus 4.5: $5/M tokens input, $25/M tokens output
• GPT-5.1 Chat: Pricing varies by provider

Provided by

• Claude Opus 4.5: Anthropic
• GPT-5.1 Chat: OpenAI

• Claude Opus 4.5 model details, providers and pricing
• GPT-5.1 Chat model details, providers and pricing