Claude Sonnet 5.5 vs DeepSeek Flash (4.1)
Claude Sonnet 5.5 scores higher on the Models at Work leaderboard (84 vs 70 out of 100). DeepSeek Flash (4.1) is about 7.6× cheaper per blended million tokens ($0.52 vs $4).
| Claude Sonnet 5.5 · Anthropic | DeepSeek Flash (4.1) · DeepSeek | |
|---|---|---|
| Leaderboard rank | #4 | #9 |
| Score (0–100) | 84 | 70 |
| Tier | Workhorse | Fast and cheap |
| Price per 1M tokens | $2 in · $10 out | $0.30 in · $1.20 out |
| Context window | 1M | 1M |
| Open weights | No | Not verified |
| Artificial Analysis Intelligence Index | 56 | — |
| Best for | Production coding assistants, High-volume agents, Default model for most teams | Cheap coding tiers, Bulk generation, Experiments where data residency is not a constraint |
Choose Claude Sonnet 5.5 if…
- you need production coding assistants
- you need high-volume agents
- you need default model for most teams
The value pick of the table: second on the index at a fifth of the Opus price, and the fastest of the top five.
Choose DeepSeek Flash (4.1) if…
- you need cheap coding tiers
- you need bulk generation
- you need experiments where data residency is not a constraint
The reason a thousand people argued on Hacker News this week: frontier-adjacent coding for pocket change, with the caveats you would expect.
Caveats: Open-weights status and licence not verified from a primary source at time of writing. Off-peak and peak pricing differ; the cheap numbers are off-peak. Data handling terms should be read before any enterprise use.
What practitioners say
Claude Sonnet 5.5: Less discussed than its siblings because it just works; the October cache-read price cut to $0.10 per million was the news.
DeepSeek Flash (4.1): The 'why isn't the industry freaking out' post hit 1,067 points; the most-upvoted replies say the price is real and the coding gap to Opus is also real.
Questions people ask
Which is better, Claude Sonnet 5.5 or DeepSeek Flash (4.1)?
Claude Sonnet 5.5 scores higher on the Models at Work leaderboard (84 vs 70 out of 100). DeepSeek Flash (4.1) is about 7.6× cheaper per blended million tokens ($0.52 vs $4).
When should I choose Claude Sonnet 5.5 over DeepSeek Flash (4.1)?
Choose Claude Sonnet 5.5 for production coding assistants, high-volume agents, default model for most teams. The value pick of the table: second on the index at a fifth of the Opus price, and the fastest of the top five.
When should I choose DeepSeek Flash (4.1) over Claude Sonnet 5.5?
Choose DeepSeek Flash (4.1) for cheap coding tiers, bulk generation, experiments where data residency is not a constraint. The reason a thousand people argued on Hacker News this week: frontier-adjacent coding for pocket change, with the caveats you would expect.
Which is cheaper, Claude Sonnet 5.5 or DeepSeek Flash (4.1)?
Claude Sonnet 5.5 costs $2 per million input tokens and $10 per million output tokens on Anthropic's list price (Claude pricing, read Oct 10, 2026). DeepSeek Flash (4.1) costs $0.30 per million input tokens and $1.20 per million output tokens on DeepSeek's list price (DeepSeek API pricing, read Oct 10, 2026).
Scores come from the Models at Work leaderboard: Score is 0 to 100: 50% independent evals normalised within this table, 20% price-performance, 15% practitioner sentiment from Signals and community threads, 15% operational fit (context, speed, availability, open weights). Models within three points are a tie in practice. Vendor-published figures are labelled as such and never counted as independent. Prices are vendor list prices where published; blended figures assume three input tokens per output token.