Comparison
Claude Sonnet 5 vs GPT-5.1
How Claude Sonnet 5 and GPT-5.1 compare on the numbers that decide the call - and how to switch between them without touching your code.
| Spec | Claude Sonnet 5 | GPT-5.1 |
|---|---|---|
| Input price / 1Mlower is cheaper | $2 | $1.25 |
| Output price / 1Mlower is cheaper | $10 | $10 |
| Context windowbigger fits more | 1M | 400K |
| Typical speedfaster median | 980ms | 1.4s |
| Quality score | 93/100 | 95/100 |
| Provider | Anthropic | OpenAI |
Which should you pick?
- GPT-5.1 is cheaper on input tokens ($1.25 vs $2).
- Claude Sonnet 5 takes a larger context window (1M tokens).
- Claude Sonnet 5 is usually the faster to answer.
- GPT-5.1 scores higher on the composite quality benchmark.
You do not have to choose permanently. Name one as your first choice and let Final Router fall back to the other when a provider fails - the request still gets answered, and the log shows which model replied.
Common questions
- Is Claude Sonnet 5 or GPT-5.1 cheaper?
- GPT-5.1 is cheaper on input tokens - $1.25 vs $2 per 1M. Neither is marked up: Final Router bills provider list price.
- Can I switch between Claude Sonnet 5 and GPT-5.1 without changing my code?
- Yes. Both are called through the same OpenAI-compatible endpoint - change only the model id ("anthropic/claude-sonnet-5" or "openai/gpt-5.1"), or let a routing policy fall back from one to the other automatically.