Claude Sonnet 5.5 vs DeepSeek V4 Flash
Claude Sonnet 5.5 
DeepSeek V4 Flash Verdict
- Claude Sonnet 5.5 (max) leads on quality: 67.6 vs 60.6.
- Claude Sonnet 5.5 (max) is stronger in agents & tools, coding, composite, knowledge, long context, maths, reasoning.
- DeepSeek V4 Flash (max) is stronger in instruction following.
- DeepSeek V4 Flash (max) is 24× cheaper ($0.168 vs $4.00 per 1M blended).
- DeepSeek V4 Flash (max) streams 1.6× faster (222 vs 141 tokens per second).
| Metric | Claude Sonnet 5.5 (max) | DeepSeek V4 Flash (max) |
|---|---|---|
| BenchLeader Index | 67.6 | 60.6 |
| Agents & tools score | 69.5 | 67.2 |
| Coding score | 69.8 | 47.4 |
| Composite score | 72.6 | 68.4 |
| Knowledge score | 65.4 | 55.3 |
| Long context score | 66.6 | 65.0 |
| Maths score | 72.9 | 57.3 |
| Reasoning score | 81.1 | 68.8 |
| Instruction following score | – | 76.7 |
| Blended price $/M | $4.00 | $0.168 |
| Output speed | 141 tok/s | 222 tok/s |
| Time to first answer | 487.1 s | 9.9 s |
| Context window | 1M | 1M |
| GPQA Diamond | 95.6% | – |
| FrontierMath Tiers 1–3 | 88.8% | – |
| FrontierMath Tier 4 | 80.5% | – |
| OTIS Mock AIME | 100.0% | – |
| SimpleQA Verified | 46.5% | – |
| Terminal-Bench | 61.8% | – |
| SciCode | 61.0% | 44.9% |
| WeirdML | – | 45.6% |
| APEX-Agents | 75.5% | – |
| ProofBench | 100.0% | – |
| LMArena Agent | 12 | – |
| LiveBench | 75.7% | – |
| LiveBench Reasoning | 91.6% | – |
| LiveBench Coding | 91.4% | – |
| LiveBench Agentic Coding | 56.3% | – |
| LiveBench Mathematics | 96.1% | – |
| LiveBench Data Analysis | 59.5% | – |
| LiveBench Language | 78.0% | – |
| LiveBench Instruction Following | 56.8% | – |
| AA Intelligence Index v4.3.2 | 56 | 34.3 |
| IFBench | – | 79.2% |
| AA-LCR | 82.7% | 79.7% |
| AA-Omniscience | 32.3 | -14.3 |
| Terminal-Bench Hard | – | 35.6% |
| GPQA Diamond (AA) | – | 90.8% |
| Humanity's Last Exam (AA) | 55.0% | 38.5% |
| SciCode (AA) | 61.0% | 50.4% |
| τ²-Bench Telecom (AA) | – | 95.0% |
| AIME 2026 | – | 95.8% |
| HMMT February 2026 | – | 93.9% |
| MathArena Apex | – | 27.1% |
| CritPt | 31.4% | 16.6% |
| GDPval-AA v2.1 | 67.0% | 46.9% |
| τ³-Banking (AA) | – | 39.4% |
| ITBench SRE (AA) | – | 31.5% |
| Analyst Agent (AA) | 57.5% | 25.0% |
| Mystery Game Puzzles | 65.0% | – |
| LMCA | – | 35.9% |
| DTBench | – | 86.4% |
| CursorBench | 55.5% | – |
| FrontierSWE | 61.9% | – |
| Terminal-Bench 4.0 (AA) | 63.6% | 12.1% |
| Terminal-Bench 2.1 (AA) | – | 78.7% |
| AutomationBench | 71.8% | – |
| GDP.pdf | 25.8% | – |
| MLCR | 75.0% | – |
| Harvey LAB | 2.8% | – |
| AA-Omniscience: accuracy | 54.0% | 40.4% |
| AA-Omniscience: non-hallucination | 53.0% | 8.3% |
| AA-Briefcase v1.1 | 1823 | – |
Data as of 2026-10-11. Best configuration of each model; every score links to its source on the model pages.
Claude Sonnet 5.5 vs DeepSeek V4 Flash: questions
- Is Claude Sonnet 5.5 better than DeepSeek V4 Flash?
- Claude Sonnet 5.5 (max) leads on quality: 67.6 vs 60.6. The BenchLeader Index combines every independent quality benchmark; Claude Sonnet 5.5 (max) is ahead overall as of 2026-10-11, but check the category scores for your use.
- Is Claude Sonnet 5.5 better than DeepSeek V4 Flash for coding?
- Claude Sonnet 5.5 scores higher in coding (70 vs 47 on the category index, where 50 is average).
- Is Claude Sonnet 5.5 better than DeepSeek V4 Flash for agentic tasks?
- Claude Sonnet 5.5 scores higher in agentic tasks (70 vs 67 on the category index, where 50 is average).
- Which is cheaper, Claude Sonnet 5.5 or DeepSeek V4 Flash?
- DeepSeek V4 Flash is cheaper: $0.168 against $4.00 per million tokens, blended at three input tokens per output token.
- Which is faster, Claude Sonnet 5.5 or DeepSeek V4 Flash?
- DeepSeek V4 Flash streams faster: 222 against 141 output tokens per second.
- Which has the larger context window?
- Both accept 1M tokens of context.