Claude Sonnet 4.5 vs DeepSeek V4.1 Flash
DeepSeek V4.1 Flash leads Claude Sonnet 4.5 on coding, 62.5 to 39.5 on the Vibe Coding Index, and DeepSeek V4.1 Flash costs 17.9x less per output token ($0.84 vs $15.00 per million). Updated October 22, 2026; 58 benchmarks have a result for both.
vs boards won of 58 shared
Claude Sonnet 4.5 or DeepSeek V4.1 Flash: which to pick
Pick DeepSeek V4.1 Flash for coding: it scores 62.5 on the Vibe Coding Index against 39.5 for Claude Sonnet 4.5.
Pick Claude Sonnet 4.5 for work measured by LegalBench (Vals AI) or MedCode (Vals AI), where it leads.
Model AClaude Sonnet 4.5Anthropic39.5/1003 independent benchmarks$1.16 per solved taskModel BDeepSeek V4.1 FlashDeepSeek62.5/1005 independent benchmarksNo cost per solved task
- Shared results
- 58
- Claude Sonnet 4.5 only
- 37
- DeepSeek V4.1 Flash only
- 43
- Like-for-like categories
- 7 of 9
Only benchmarks that tested both models count toward a pick; a result only one model has is shown but not compared.
Which one for your work
Each card is decided by one number both models carry. Where only one has it, the card says so and makes no call.
Coding
Vibe Coding Index, six public coding benchmarks
DeepSeek V4.1 Flash
DeepSeek V4.1 Flash scores 62.5 against 39.5.
3 and 5 benchmarks behind the scores
Intelligence
AA Intelligence Index
DeepSeek V4.1 Flash
DeepSeek V4.1 Flash leads, 24.7 against 20.7.
Same board, both measured
Agentic work
AA Agentic Index
No call
Only Claude Sonnet 4.5 has a AA Agentic Index result, 15.8.
Directional only
Reasoning
GPQA Diamond
No call
Only Claude Sonnet 4.5 has a GPQA Diamond result, 81.6%.
Directional only
Math
AIME
No call
Only Claude Sonnet 4.5 has a AIME result, 88.2%.
Directional only
Knowledge
MMLU Pro
No call
Only Claude Sonnet 4.5 has a MMLU Pro result, 87.4%.
Directional only
Web design
Design Arena: websites
DeepSeek V4.1 Flash
DeepSeek V4.1 Flash leads, 1308 against 1189.
Same board, both measured
Long documents
Listed context window
DeepSeek V4.1 Flash
DeepSeek V4.1 Flash takes 1.05M tokens against 1M.
Listed by OpenRouter
Everyday cost
1K input + 500 output tokens
DeepSeek V4.1 Flash
Claude Sonnet 4.5 $0.011, DeepSeek V4.1 Flash $0.0006 per turn.
List prices
Cost per solved task
One SWE-bench Verified task, solved
No call
Only Claude Sonnet 4.5 has the number, $1.16.
Directional only
At a glance
- Coding index
- Claude Sonnet 4.5 39.5 from 3 benchmarks, DeepSeek V4.1 Flash 62.5 from 5 benchmarks.
- Widest category
- Coding, 28.3 points apart on average over 6 shared benchmarks.
- Widest single gap
- Vibe Code Bench (Vals AI): Claude Sonnet 4.5 22.6% against DeepSeek V4.1 Flash 84.7%, 62.1 points apart on a 0 to 100 scale.
- Output price
- Claude Sonnet 4.5 $15.00 against DeepSeek V4.1 Flash $0.84 per million output tokens, 17.9x apart.
- Context window
- Claude Sonnet 4.5 takes 1M tokens, DeepSeek V4.1 Flash 1.05M.
Benchmark by benchmark
First the score: boards each model leads, per category, where both have a result. Then every board, a category to a fold; bars are each result on a 0 to 100 scale, so compare the two in a row, not one row with another.
| Category | Claude Sonnet 4.5 | Bars | DeepSeek V4.1 Flash | Ties |
|---|---|---|---|---|
| Coding | 0 | 6 | ||
| Intelligence | 0 | 2 | ||
| Reasoning | 0 | 8 | ||
| Math | 0 | 6 | ||
| Knowledge | 3 | 4 | ||
| Web design | 0 | 8 | ||
| General | 3 | 18 | ||
| All shared boards | 6 | 52 |
CodingLike-for-likeSix of these boards feed the Vibe Coding Index06
| Benchmark | Claude Sonnet 4.5 | DeepSeek V4.1 Flash | Leader |
|---|---|---|---|
| SWE-bench Verified | 74.8% | Not measured | Only Claude Sonnet 4.5 measured |
| SWE-bench Multilingual | 67.0% | Not measured | Only Claude Sonnet 4.5 measured |
| LiveBench coding | Not measured | 90.2% | Only DeepSeek V4.1 Flash measured |
| LMArena WebDev | 1394 | 1618 | DeepSeek V4.1 Flash |
| AA Coding Index | 52.1 | Not measured | Only Claude Sonnet 4.5 measured |
| LiveCodeBench (Vals AI) | 73.0% | Not measured | Only Claude Sonnet 4.5 measured |
| SWE-bench Verified (Vals AI) | 70.0% | Not measured | Only Claude Sonnet 4.5 measured |
| Terminal-Bench 4 (Vals AI) | Not measured | 19.7% | Only DeepSeek V4.1 Flash measured |
| Vibe Code Bench (Vals AI) | 22.6% | 84.7% | DeepSeek V4.1 Flash |
| Code migration (Vals AI) | Not measured | 45.6% | Only DeepSeek V4.1 Flash measured |
| ProgramBench (Vals AI) | Not measured | 0.5% | Only DeepSeek V4.1 Flash measured |
| IOI (Vals AI) | Not measured | 40.3% | Only DeepSeek V4.1 Flash measured |
| Terminal-Bench 2.1 (Vals AI) | Not measured | 74.5% | Only DeepSeek V4.1 Flash measured |
| SWE-bench Multimodal (Vals AI) | Not measured | 46.5% | Only DeepSeek V4.1 Flash measured |
| Vibe Code Bench 1-100 (Vals AI) | Not measured | 16.4% | Only DeepSeek V4.1 Flash measured |
| SkillsBench (Vals AI) | Not measured | 69.8% | Only DeepSeek V4.1 Flash measured |
| CyberBench (Vals AI) | Not measured | 73.7% | Only DeepSeek V4.1 Flash measured |
| SciCode | Not measured | 51.9% | Only DeepSeek V4.1 Flash measured |
| Terminal-Bench | 46.5% | Not measured | Only Claude Sonnet 4.5 measured |
| FrontierCode | Not measured | 43.9% | Only DeepSeek V4.1 Flash measured |
| GSO-Bench | 14.7% | Not measured | Only Claude Sonnet 4.5 measured |
| WeirdML | 47.7% | Not measured | Only Claude Sonnet 4.5 measured |
| Cybench | 60.0% | Not measured | Only Claude Sonnet 4.5 measured |
| ALE-Bench | Not measured | 1092.3 | Only DeepSeek V4.1 Flash measured |
| LMArena Text: coding | 1488 | 1502 | DeepSeek V4.1 Flash |
| LMArena Text: software and IT | 1473 | 1496 | DeepSeek V4.1 Flash |
| LMArena WebDev: React | 1386 | 1628 | DeepSeek V4.1 Flash |
| LMArena WebDev: HTML | 1399 | 1612 | DeepSeek V4.1 Flash |
| LMArena WebDev: from an image | Not measured | 1606 | Only DeepSeek V4.1 Flash measured |
| Neither model has a result on the other 10 boards here | |||
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index02
| Benchmark | Claude Sonnet 4.5 | DeepSeek V4.1 Flash | Leader |
|---|---|---|---|
| AA Intelligence Index | 20.7 | 24.7 | DeepSeek V4.1 Flash |
| Epoch Capabilities Index | 146.7 | 155.9 | DeepSeek V4.1 Flash |
Agentic workDirectional onlyPublic boards, shown as published, kept out of the index23 boards, none shared
| Benchmark | Claude Sonnet 4.5 | DeepSeek V4.1 Flash | Leader |
|---|---|---|---|
| AA Agentic Index | 15.8 | Not measured | Only Claude Sonnet 4.5 measured |
| Design Arena: agents building web apps | 1060 | Not measured | Only Claude Sonnet 4.5 measured |
| Design Arena: agents building full-stack apps | 1050 | Not measured | Only Claude Sonnet 4.5 measured |
| Design Arena: agents building mobile apps | 1137 | Not measured | Only Claude Sonnet 4.5 measured |
| LiveBench research | Not measured | 86.8% | Only DeepSeek V4.1 Flash measured |
| LiveBench browser | Not measured | 84.0% | Only DeepSeek V4.1 Flash measured |
| LiveBench long agentic | Not measured | 40.1% | Only DeepSeek V4.1 Flash measured |
| SREBench (Vals AI) | Not measured | 0.8% | Only DeepSeek V4.1 Flash measured |
| Finance Agent (Vals AI) | Not measured | 53.5% | Only DeepSeek V4.1 Flash measured |
| Tax Agent Bench (Vals AI) | Not measured | 26.6% | Only DeepSeek V4.1 Flash measured |
| Legal Research Bench (Vals AI) | Not measured | 41.4% | Only DeepSeek V4.1 Flash measured |
| Excel Modeling Benchmark (Vals AI) | Not measured | 57.2% | Only DeepSeek V4.1 Flash measured |
| BioMysteryBench (Vals AI) | Not measured | 67.8% | Only DeepSeek V4.1 Flash measured |
| Terminal-Bench-Science (Vals AI) | Not measured | 0.0% | Only DeepSeek V4.1 Flash measured |
| Vals Science Index | Not measured | 29.6% | Only DeepSeek V4.1 Flash measured |
| APEX-Agents | Not measured | 39.5% | Only DeepSeek V4.1 Flash measured |
| METR time horizons | 67.4% | Not measured | Only Claude Sonnet 4.5 measured |
| Remote Labor Index | 2.1% | Not measured | Only Claude Sonnet 4.5 measured |
| GDPval | 42.5% | Not measured | Only Claude Sonnet 4.5 measured |
| DeepResearch Bench | 52.6% | Not measured | Only Claude Sonnet 4.5 measured |
| OSWorld | 62.9% | Not measured | Only Claude Sonnet 4.5 measured |
| Vending-Bench 2 | $3,839 | Not measured | Only Claude Sonnet 4.5 measured |
| Berkeley Function Calling Leaderboard (BFCL) | 73.2% | Not measured | Only Claude Sonnet 4.5 measured |
| Neither model has a result on the other 18 boards here | |||
ReasoningLike-for-likePublic boards, shown as published, kept out of the index08
| Benchmark | Claude Sonnet 4.5 | DeepSeek V4.1 Flash | Leader |
|---|---|---|---|
| GPQA Diamond | 81.6% | Not measured | Only Claude Sonnet 4.5 measured |
| LiveBench reasoning | Not measured | 86.7% | Only DeepSeek V4.1 Flash measured |
| MysteryMechanism (Vals AI) | Not measured | 21.2% | Only DeepSeek V4.1 Flash measured |
| MMMU Pro (Vals AI) | 79.3% | Not measured | Only Claude Sonnet 4.5 measured |
| Humanity's Last Exam (Artificial Analysis run) | Not measured | 39.2% | Only DeepSeek V4.1 Flash measured |
| GPQA Diamond (Epoch AI run) | 82.3% | 89.8% | DeepSeek V4.1 Flash |
| ARC-AGI | 63.7% | 94.5% | DeepSeek V4.1 Flash |
| ARC-AGI-2 | 13.6% | 72.9% | DeepSeek V4.1 Flash |
| SimpleBench | 54.3% | Not measured | Only Claude Sonnet 4.5 measured |
| Chess puzzles | 10.0% | 48.0% | DeepSeek V4.1 Flash |
| Mystery game puzzles | 17.0% | 43.0% | DeepSeek V4.1 Flash |
| EBR-bench | 2.4% | Not measured | Only Claude Sonnet 4.5 measured |
| VPCT | 39.8% | Not measured | Only Claude Sonnet 4.5 measured |
| LMArena Text: hard prompts | 1462 | 1483 | DeepSeek V4.1 Flash |
| LMArena Text: expert | 1483 | 1501 | DeepSeek V4.1 Flash |
| LMArena Text: hard prompts in English | 1471 | 1488 | DeepSeek V4.1 Flash |
| LMArena Vision: diagrams | Not measured | 1297 | Only DeepSeek V4.1 Flash measured |
| LMArena Vision: homework | Not measured | 1307 | Only DeepSeek V4.1 Flash measured |
| Kagi LLM Benchmark | 57.9% | Not measured | Only Claude Sonnet 4.5 measured |
| Neither model has a result on the other 3 boards here | |||
MathLike-for-likePublic boards, shown as published, kept out of the index06
| Benchmark | Claude Sonnet 4.5 | DeepSeek V4.1 Flash | Leader |
|---|---|---|---|
| AIME | 88.2% | Not measured | Only Claude Sonnet 4.5 measured |
| MGSM (Vals AI) | 94.3% | Not measured | Only Claude Sonnet 4.5 measured |
| OTIS Mock AIME | 77.8% | 98.3% | DeepSeek V4.1 Flash |
| FrontierMath, tiers 1 to 3 | 23.9% | 67.4% | DeepSeek V4.1 Flash |
| FrontierMath, tier 4 | 2.4% | 26.8% | DeepSeek V4.1 Flash |
| ProofBench | 19.0% | 54.0% | DeepSeek V4.1 Flash |
| MATH level 5 | 97.7% | Not measured | Only Claude Sonnet 4.5 measured |
| LMArena Text: math | 1449 | 1478 | DeepSeek V4.1 Flash |
| LMArena Text: mathematical work | 1462 | 1485 | DeepSeek V4.1 Flash |
| Neither model has a result on the other 4 boards here | |||
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index34
| Benchmark | Claude Sonnet 4.5 | DeepSeek V4.1 Flash | Leader |
|---|---|---|---|
| MMLU Pro | 87.4% | Not measured | Only Claude Sonnet 4.5 measured |
| LegalBench (Vals AI) | 84.1% | 83.3% | Claude Sonnet 4.5 |
| CaseLaw (Vals AI) | 62.2% | Not measured | Only Claude Sonnet 4.5 measured |
| CorpFin (Vals AI) | 62.0% | Not measured | Only Claude Sonnet 4.5 measured |
| TaxEval (Vals AI) | 73.3% | Not measured | Only Claude Sonnet 4.5 measured |
| MortgageTax (Vals AI) | 64.0% | Not measured | Only Claude Sonnet 4.5 measured |
| MedQA (Vals AI) | 94.7% | Not measured | Only Claude Sonnet 4.5 measured |
| MedCode (Vals AI) | 44.1% | 41.2% | Claude Sonnet 4.5 |
| SimpleQA Verified | 30.7% | 42.9% | DeepSeek V4.1 Flash |
| LMArena Text: science | 1448 | 1469 | DeepSeek V4.1 Flash |
| LMArena Text: medicine and healthcare | 1444 | 1484 | DeepSeek V4.1 Flash |
| LMArena Text: legal and government | 1451 | 1443 | Claude Sonnet 4.5 |
| LMArena Text: business and finance | 1440 | 1461 | DeepSeek V4.1 Flash |
| FACTS Benchmark Suite | 40.6% | Not measured | Only Claude Sonnet 4.5 measured |
| Neither model has a result on the other 4 boards here | |||
Web designLike-for-likePublic boards, shown as published, kept out of the index08
| Benchmark | Claude Sonnet 4.5 | DeepSeek V4.1 Flash | Leader |
|---|---|---|---|
| Design Arena: websites | 1189 | 1308 | DeepSeek V4.1 Flash |
| Design Arena: UI components | 1170 | 1312 | DeepSeek V4.1 Flash |
| Design Arena: game dev | 1166 | 1330 | DeepSeek V4.1 Flash |
| Design Arena: data viz | 1167 | 1291 | DeepSeek V4.1 Flash |
| Design Arena: 3D | 1157 | 1355 | DeepSeek V4.1 Flash |
| Design Arena: all code categories | 1182 | 1320 | DeepSeek V4.1 Flash |
| Design Arena: SVG | 1115 | 1245 | DeepSeek V4.1 Flash |
| Design Arena: ASCII art | 1205 | 1265 | DeepSeek V4.1 Flash |
| LiveBench design | Not measured | 79.2% | Only DeepSeek V4.1 Flash measured |
GeneralLike-for-likePublic boards, shown as published, kept out of the index318
| Benchmark | Claude Sonnet 4.5 | DeepSeek V4.1 Flash | Leader |
|---|---|---|---|
| LiveBench data analysis | Not measured | 79.3% | Only DeepSeek V4.1 Flash measured |
| Public Benefits Bench (Vals AI) | Not measured | 64.3% | Only DeepSeek V4.1 Flash measured |
| SAGE (Vals AI) | 36.1% | 47.9% | DeepSeek V4.1 Flash |
| MedScribe (Vals AI) | 84.5% | 85.5% | DeepSeek V4.1 Flash |
| Long context reasoning (AA-LCR) | Not measured | 84.0% | Only DeepSeek V4.1 Flash measured |
| DTBench | 83.2% | 89.9% | DeepSeek V4.1 Flash |
| LMCA | 38.8% | 47.0% | DeepSeek V4.1 Flash |
| Surface Evolver Bench | Not measured | 46.3% | Only DeepSeek V4.1 Flash measured |
| Furniture assembly | Not measured | 34.2% | Only DeepSeek V4.1 Flash measured |
| LMArena Text | 1438 | 1464 | DeepSeek V4.1 Flash |
| LMArena Text: instruction following | 1459 | 1473 | DeepSeek V4.1 Flash |
| LMArena Text: creative writing | 1442 | 1437 | Claude Sonnet 4.5 |
| LMArena Vision | Not measured | 1278 | Only DeepSeek V4.1 Flash measured |
| LMArena Text: English | 1450 | 1473 | DeepSeek V4.1 Flash |
| LMArena Text: non-English | 1425 | 1449 | DeepSeek V4.1 Flash |
| LMArena Text: Chinese | 1460 | 1501 | DeepSeek V4.1 Flash |
| LMArena Text: German | 1427 | 1470 | DeepSeek V4.1 Flash |
| LMArena Text: Japanese | 1390 | 1432 | DeepSeek V4.1 Flash |
| LMArena Text: Korean | 1402 | 1436 | DeepSeek V4.1 Flash |
| LMArena Text: French | 1459 | 1465 | DeepSeek V4.1 Flash |
| LMArena Text: Spanish | 1458 | 1459 | DeepSeek V4.1 Flash |
| LMArena Text: Russian | 1437 | 1467 | DeepSeek V4.1 Flash |
| LMArena Text: Polish | 1423 | 1457 | DeepSeek V4.1 Flash |
| LMArena Text: multi-turn | 1465 | 1461 | Claude Sonnet 4.5 |
| LMArena Text: longer queries | 1475 | 1473 | Claude Sonnet 4.5 |
| LMArena Text: writing and language | 1442 | 1450 | DeepSeek V4.1 Flash |
| LMArena Text: entertainment and media | 1428 | 1445 | DeepSeek V4.1 Flash |
| LMArena Vision: English | Not measured | 1288 | Only DeepSeek V4.1 Flash measured |
| LMArena Vision: Chinese | Not measured | 1327 | Only DeepSeek V4.1 Flash measured |
| LMArena Vision: reading text | Not measured | 1282 | Only DeepSeek V4.1 Flash measured |
| LMArena Vision: humor | Not measured | 1260 | Only DeepSeek V4.1 Flash measured |
| LMArena Vision: creative writing | Not measured | 1275 | Only DeepSeek V4.1 Flash measured |
| LMArena Document | 1450 | Not measured | Only Claude Sonnet 4.5 measured |
| Neither model has a result on the other 13 boards here | |||
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
| Benchmark | Claude Sonnet 4.5 | DeepSeek V4.1 Flash | Leader |
|---|---|---|---|
| Neither model has a result on 5 boards here | |||
What each workload costs
Three fixed token mixes at each model's listed price, so per-token rates become a bill.
Chat turn
1K input + 500 output tokens
Claude Sonnet 4.5$0.011Fits in one request
DeepSeek V4.1 Flash$0.0006Fits in one request
DeepSeek V4.1 Flash costs less
Repository review
50K input + 3K output tokens
Claude Sonnet 4.5$0.195Fits in one request
DeepSeek V4.1 Flash$0.014Fits in one request
DeepSeek V4.1 Flash costs less
Agent loop
200K input + 10K output tokens
Claude Sonnet 4.5$0.750Fits in one request
DeepSeek V4.1 Flash$0.053Fits in one request
DeepSeek V4.1 Flash costs less
Listed OpenRouter rates, without cache or batch discounts. A workload that does not fit a model's context window would need splitting.
Specification differences
The leading value in a row is marked; a row with a missing value names no leader. Our two rows are marked in red.
| Specification | Anthropic Claude Sonnet 4.5 | DeepSeek V4.1 Flash |
|---|---|---|
| Maker | Anthropic | DeepSeek |
| Weights | No public weights listed | Open weights |
| Released | September 29, 2025 | September 10, 2026 |
| Context window | 1M | 1.05M |
| Input $/Mtok | $3.00 | $0.2225 |
| Output $/Mtok | $15.00 | $0.84 |
| Coding index | 39.5 | 62.5 |
| Independent measurements behind it | 3 | 5 |
| Cost per solved task | $1.16 | Not computable |
| Source | OpenRouter listing | OpenRouter listing |
Questions
Is Claude Sonnet 4.5 better than DeepSeek V4.1 Flash for coding?
Pick DeepSeek V4.1 Flash for coding: it scores 62.5 on the Vibe Coding Index against 39.5 for Claude Sonnet 4.5. Pick Claude Sonnet 4.5 for work measured by LegalBench (Vals AI) or MedCode (Vals AI), where it leads.
Which is cheaper, Claude Sonnet 4.5 or DeepSeek V4.1 Flash?
Claude Sonnet 4.5 costs $3.00 per million input tokens and $15.00 per million output tokens; DeepSeek V4.1 Flash costs $0.2225 and $0.84. Cost per solved task is known for Claude Sonnet 4.5 only.
Which has the bigger context window, Claude Sonnet 4.5 or DeepSeek V4.1 Flash?
DeepSeek V4.1 Flash, with 1.05M tokens against 1M.
How many benchmarks is the Claude Sonnet 4.5 vs DeepSeek V4.1 Flash comparison based on?
58 benchmarks have a result for both models as of October 22, 2026. Claude Sonnet 4.5's coding index rests on 3 independent benchmarks and DeepSeek V4.1 Flash's on 5. Where only one model has a result, the page says so instead of naming a winner.