DeepSeek-V4.1-Flash vs Claude Sonnet 5
DeepSeek-V4.1-Flash wins on Overall, Coding, Multimodal. Every numeric field is compared below, with a worked monthly-cost example and a pick rule for each use case.
Verdict at a glance
Choose DeepSeek-V4.1-Flash if you…
- 1M context at ~890 bytes/token global KV
- Top agentic coding (DeepSWE 74.2, Terminal-Bench 2.1 90.6)
- Persistent KV cut to ~1/8 via bounded replay
- Open weights, extremely low serving cost
- Best for: Long-context AI agents, Agentic coding, High-throughput deployment
Choose Claude Sonnet 5 if you…
- Fast
- Moderately priced
- Anthropic quality
- Value flagship
- Best for: Daily tasks, Fast responses, Coding
Head-to-head aggregate scores
Scores are 0–100, aggregated from public benchmark information and independently weighted across three leaderboards. Rank is out of 27 tracked models.
Aggregated from public sources and independently weighted; methodology on the Terms page. Scores within 3 points are treated as statistically tied.
Specs & pricing — every field side by side
List API prices in USD per 1M tokens. The highlighted cell is the stronger value/capability on that row.
| Dimension | DeepSeek-V4.1-Flash | Claude Sonnet 5 | Verdict |
|---|---|---|---|
| Vendor | DeepSeek (CN) | Anthropic (US) | Different vendors |
| Released | 2026.09 | 2026.06 | DeepSeek-V4.1-Flash is newer |
| Overall (rank) | 76 · #12 | 71 · #16 | DeepSeek-V4.1-Flash +5 |
| Coding | 89 · #5 | 73 · #14 | DeepSeek-V4.1-Flash +16 |
| Multimodal | 78 · #16 | 76 · #18 | DeepSeek-V4.1-Flash +2 |
| Context window | 1M | 1M | Tie |
| Max output | 128K | 128K | Tie |
| Effective-context | 98 | 95 | DeepSeek-V4.1-Flash more reliable |
| Input $/1M | $0.14 | $3 | DeepSeek-V4.1-Flash cheaper |
| Output $/1M | $0.28 | $15 | DeepSeek-V4.1-Flash cheaper |
| Cache discount | none | 90% off | Claude Sonnet 5 deeper |
| Speed | ~85 tok/s | ~65 tok/s | DeepSeek-V4.1-Flash faster |
| TTFT | 0.3s | 0.5s | DeepSeek-V4.1-Flash snappier |
| Function calling | 84 | 88 | Claude Sonnet 5 ahead |
| Refusal rate | ~5% | ~8% | DeepSeek-V4.1-Flash less restrictive |
| English | 84 | 90 | Claude Sonnet 5 |
| Chinese | 86 | 78 | DeepSeek-V4.1-Flash |
| Modalities | text, image | text, image | Same |
| Open weights | Yes | No | DeepSeek-V4.1-Flash is open |
| Fine-tuning | Yes | No | |
| Free tier | DeepSeek App free; open weights to self-host | No free tier | |
| SOC2 / no-train | no / yes | yes / yes | |
| Private deployment | Yes | No | DeepSeek-V4.1-Flash |
Fields drawn from vendor public documentation and the Modelspectra 27-model dataset; speed varies with network, concurrency and prompt length. Verify current pricing before purchase.
Dimension-by-dimension analysis
Reasoning & overall intelligence
DeepSeek-V4.1-Flash leads the overall aggregate by 5 points (76 vs 71). That is a meaningful, not marginal, edge on hard, multi-step reasoning, while Claude Sonnet 5 remains a strong generalist that is not out of its depth on routine work.
Agentic coding
This is a clear gap: DeepSeek-V4.1-Flash scores 89 against 73. On multi-file edits, SWE-style tickets and long-horizon agent loops DeepSeek-V4.1-Flash needs fewer correction turns; Claude Sonnet 5 is still competent for scripts and assisted completion but trails as task complexity rises.
Multimodal
DeepSeek-V4.1-Flash leads multimodal 78 vs 76. Neither emits native video, so the comparison is about parsing images and documents, not generation.
Speed & latency
DeepSeek-V4.1-Flash is faster in interactive use: ~85 tok/s with 0.3s TTFT versus ~65 tok/s with 0.5s TTFT (about 1.3× the throughput). For conversational UIs where perceived responsiveness drives retention, that edge is a real product factor even when raw reasoning is lower.
Context: window vs usable recall
Nominal windows are 1M for DeepSeek-V4.1-Flash and 1M for Claude Sonnet 5. Effective-context scores point the same way as window size — DeepSeek-V4.1-Flash is ahead on usable recall (98 vs 95), so prefer it for long-document work where details cannot be missed.
Price & total cost
DeepSeek-V4.1-Flash is the cheaper API at $0.14/$0.28 versus Claude Sonnet 5 at $3/$15 per 1M input/output tokens — list input is about 21.4× lower. Cache discounts (Claude Sonnet 5 90%) shift the effective bill, worked out below.
Chinese vs English
English: DeepSeek-V4.1-Flash 84 vs Claude Sonnet 5 90. Chinese: 86 vs 78. For Chinese-language production, DeepSeek-V4.1-Flash is the stronger pick. Note that non-Chinese models generally require overseas network access for their APIs.
Tool use & ecosystem
Function-calling score: DeepSeek-V4.1-Flash 84 vs Claude Sonnet 5 88, so Claude Sonnet 5 has the edge on structured tool use. Fine-tuning is available from DeepSeek-V4.1-Flash. Factor in existing SDK/plugin familiarity — switching cost often outweighs a few-point tool-use gap.
Cost worked example — same workload, real token math
Assume a production workload of 100M input + 30M output tokens per month, with 90% of input tokens served from cache. Figures use public list prices.
| Scenario · per month | DeepSeek-V4.1-Flash | Claude Sonnet 5 | Gap |
|---|---|---|---|
| List priceno cache applied | $22100M in × $0.14 + 30M out × $0.28 | $750100M in × $3 + 30M out × $15 | 34.09×gap |
| With caching90% of inputs cache-hit | $22no published cache discount | $50790M cached in × $0.3 + 10M in × $3 + 30M out × $15 | 23.05×gap |
Illustrative model; your input/output mix and cache-hit ratio change the result. Prices are list rates before any enterprise agreement.