Comparison
Claude Sonnet 5 vs DeepSeek V4 Flash
How Claude Sonnet 5 and DeepSeek V4 Flash compare on the numbers that decide the call - and how to switch between them without touching your code.
| Spec | Claude Sonnet 5 | DeepSeek V4 Flash |
|---|---|---|
| Input price / 1Mlower is cheaper | $2 | $0.22 |
| Output price / 1Mlower is cheaper | $10 | $0.66 |
| Context windowbigger fits more | 1M | 1M |
| Typical speedfaster median | 980ms | 700ms |
| Quality score | 93/100 | 79/100 |
| Provider | Anthropic | DeepSeek |
Which should you pick?
- DeepSeek V4 Flash is cheaper on input tokens ($0.22 vs $2).
- DeepSeek V4 Flash is usually the faster to answer.
- Claude Sonnet 5 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 DeepSeek V4 Flash cheaper?
- DeepSeek V4 Flash is cheaper on input tokens - $0.22 vs $2 per 1M. Neither is marked up: Final Router bills provider list price.
- Can I switch between Claude Sonnet 5 and DeepSeek V4 Flash without changing my code?
- Yes. Both are called through the same OpenAI-compatible endpoint - change only the model id ("anthropic/claude-sonnet-5" or "deepseek/deepseek-v4-flash"), or let a routing policy fall back from one to the other automatically.