# Claude Sonnet 4 vs DeepSeek V4.1 Flash

> DeepSeek V4.1 Flash is the stronger model overall, scoring 50.3 to 40.6 on the Noometry Index.

- Canonical page: https://noometry.com/compare/claude-sonnet-4-vs-deepseek-v4-1-flash
- Last updated: 2026-10-10
- Shared benchmarks: 21

## Summary

- They share 21 benchmarks with published results for both. Claude Sonnet 4 scores higher in 0 categories and DeepSeek V4.1 Flash in 8 categories; 7 gaps are clear of the uncertainty.
- The widest gap is in reasoning, where DeepSeek V4.1 Flash leads 46.2 to 23.0.
- The biggest single-benchmark swing is LMCA: 29% for Claude Sonnet 4 and 47% for DeepSeek V4.1 Flash.
- DeepSeek V4.1 Flash is cheaper at $0.15 / $0.60 per million input/output tokens, against $3 / $15 for Claude Sonnet 4.
- DeepSeek V4.1 Flash accepts more context: 1M tokens versus 200K.
- DeepSeek V4.1 Flash has downloadable open weights; the other is API-only.

## Snapshot

| | Claude Sonnet 4 | DeepSeek V4.1 Flash |
|---|---|---|
| Provider | Anthropic | DeepSeek |
| Noometry Index | 40.6 | 50.3 |
| Rank | 139 | 40 |
| Context | 200K | 1M |
| Input $/M | $3 | $0.15 |
| Output $/M | $15 | $0.60 |
| Weights | Proprietary | Open |

## Coding

- Claude Sonnet 4: 44.0 (#70)
- DeepSeek V4.1 Flash: 52.8 (#29)

| Benchmark | Claude Sonnet 4 | DeepSeek V4.1 Flash |
|---|---|---|
| SciCode | 40% | 51.9% |
| LMArena Coding | 1414 | 1511 |
| ALE-Bench | 655.35 | 1,092 |
| SWE-bench Verified (bash only) | 64.9% | — |
| Aider Polyglot | 61.3% | — |
| LMArena WebDev | — | 1620 |
| GSO | 4.9% | — |
| WeirdML | 46.1% | — |

## Agentic & Tool Use

- Claude Sonnet 4: 38.3 (#29)
- DeepSeek V4.1 Flash: —

| Benchmark | Claude Sonnet 4 | DeepSeek V4.1 Flash |
|---|---|---|
| TheAgentCompany | 33.1% | — |
| Cybench | 35% | — |
| DeepResearch Bench | 46.6% | — |
| OSWorld | 43.9% | — |
| METR Time Horizons | 62% | — |

## Reasoning

- Claude Sonnet 4: 23.0 (#169)
- DeepSeek V4.1 Flash: 46.2 (#39)

| Benchmark | Claude Sonnet 4 | DeepSeek V4.1 Flash |
|---|---|---|
| CritPt | 0.3% | 14.3% |
| LMArena Hard Prompts | 1372 | 1485 |
| DTBench | 77.1% | 89.9% |
| LMCA | 29% | 47% |
| Epoch Capabilities Index | 141.69 | 155.01 |
| ARC-AGI-2 | 5.9% | — |
| SimpleBench | 45.5% | — |
| Kagi LLM Benchmark | 73% | — |
| NYT Connections (extended) | — | 89.6% |
| ARC-AGI-1 | 40% | — |
| EnigmaEval | 3.1% | — |
| Surface Evolver Bench | — | 46.3% |
| ForecastBench | 60.2 | — |

## Math

- Claude Sonnet 4: 41.5 (#71)
- DeepSeek V4.1 Flash: 48.4 (#52)

| Benchmark | Claude Sonnet 4 | DeepSeek V4.1 Flash |
|---|---|---|
| LMArena Math | 1375 | 1493 |
| OTIS Mock AIME 2024-2025 | 71.1% | — |
| ProofBench | — | 54% |
| Omni-MATH | 60.2% | — |
| MATH Level 5 | 84.4% | — |
| FrontierMath (Feb 2025 set) | 4.1% | — |
| FrontierMath Tier 4 (v1) | 0% | — |

## Knowledge

- Claude Sonnet 4: 41.6 (#99)
- DeepSeek V4.1 Flash: 41.6 (#97)

| Benchmark | Claude Sonnet 4 | DeepSeek V4.1 Flash |
|---|---|---|
| LMArena Expert | 1371 | 1505 |
| GPQA Diamond | 79.2% | — |
| Humanity's Last Exam | 7.8% | — |
| MMLU-Pro | 84.3% | — |
| Confabulations | 13.2% | — |
| Vectara Hallucination Rate | 10.3% | — |
| GPQA (HELM) | 70.6% | — |

## Multimodal

- Claude Sonnet 4: 25.6 (#116)
- DeepSeek V4.1 Flash: —

| Benchmark | Claude Sonnet 4 | DeepSeek V4.1 Flash |
|---|---|---|
| LMArena Vision | 1191 | — |
| GeoBench | 37% | — |
| VPCT | 34% | — |
| MindCube | 44.8% | — |

## Multilingual

- Claude Sonnet 4: 46.9 (#151)
- DeepSeek V4.1 Flash: 55.5 (#29)

| Benchmark | Claude Sonnet 4 | DeepSeek V4.1 Flash |
|---|---|---|
| LMArena Non-English | 1333 | 1452 |
| LMArena Chinese | 1351 | 1506 |
| LMArena French | 1364 | 1448 |
| LMArena Russian | 1355 | 1473 |
| LMArena Spanish | 1356 | 1499 |
| LMArena German | 1331 | — |
| LMArena Japanese | 1301 | — |
| LMArena Korean | 1293 | — |

## Instruction Following

- Claude Sonnet 4: 71.8 (#141)
- DeepSeek V4.1 Flash: 77.6 (#24)

| Benchmark | Claude Sonnet 4 | DeepSeek V4.1 Flash |
|---|---|---|
| LMArena Instruction Following | 1375 | 1475 |
| IFEval | 84% | — |

## Long Context

- Claude Sonnet 4: 33.6 (#254)
- DeepSeek V4.1 Flash: 45.2 (#46)

| Benchmark | Claude Sonnet 4 | DeepSeek V4.1 Flash |
|---|---|---|
| LMArena Longer Query | 1398 | 1476 |
| Fiction.LiveBench | 46.9% | — |

## Writing & Preference

- Claude Sonnet 4: 57.3 (#127)
- DeepSeek V4.1 Flash: 65.8 (#43)

| Benchmark | Claude Sonnet 4 | DeepSeek V4.1 Flash |
|---|---|---|
| LMArena Text | 1351 | 1465 |
| LMArena Creative Writing | 1345 | 1436 |
| EQ-Bench Creative Writing | 1483 | 1540 |
| LMArena Multi-Turn | 1376 | 1460 |
| Short-Story Creative Writing | 81.4% | — |
| WildBench | 83.8% | — |

## FAQ

### Is Claude Sonnet 4 better than DeepSeek V4.1 Flash?

DeepSeek V4.1 Flash is the stronger model overall, scoring 50.3 to 40.6 on the Noometry Index.

### Which is cheaper, Claude Sonnet 4 or DeepSeek V4.1 Flash?

DeepSeek V4.1 Flash is cheaper. It lists at $0.15 per million input tokens and $0.60 per million output tokens; Claude Sonnet 4 lists at $3 and $15.

### Is Claude Sonnet 4 or DeepSeek V4.1 Flash better for coding?

DeepSeek V4.1 Flash scores higher on coding benchmarks: 52.8 versus 44.0 in the Noometry coding category.

### Which has the bigger context window?

DeepSeek V4.1 Flash does, with 1M tokens against 200K.

### How many benchmarks do Claude Sonnet 4 and DeepSeek V4.1 Flash share?

21 benchmarks have published results for both models. Claude Sonnet 4 has 58 scored results on Noometry and DeepSeek V4.1 Flash has 25.