Claude Sonnet 4.5 vs GPT-5 Pro: side-by-side summary

Claude Sonnet 4.5 and GPT-5 Pro are available through the OpenRouter API, so switching between them takes a model slug change rather than a new integration.

Claude Sonnet 4.5, from Anthropic, has a 1,000,000-token context window and is priced at $3/M tokens input, $15/M tokens output on OpenRouter.

GPT-5 Pro, from OpenAI, has a 400,000-token context window and is priced at $15/M tokens input, $120/M tokens output on OpenRouter.

Context window

• Claude Sonnet 4.5: 1,000,000 tokens
• GPT-5 Pro: 400,000 tokens

Price

• Claude Sonnet 4.5: $3/M tokens input, $15/M tokens output
• GPT-5 Pro: $15/M tokens input, $120/M tokens output

Provided by

• Claude Sonnet 4.5: Anthropic
• GPT-5 Pro: OpenAI

• Claude Sonnet 4.5 model details, providers and pricing
• GPT-5 Pro model details, providers and pricing