Claude Opus 4.5 vs DeepSeek V4.1 Flash
Updated October 21, 2026. 61 benchmarks have a result for both. Coding is ranked on the Vibe Coding Index; every other board is shown as published.
vs boards won of 61 shared, 1 tied
Decision reading
Pick DeepSeek V4.1 Flash for coding: it scores 77.2 on the Vibe Coding Index against 66.8 for Claude Opus 4.5.
Pick Claude Opus 4.5 when what matters is LMArena Text: coding or AA Intelligence Index, where it leads.
Model AClaude Opus 4.5Anthropic66.8/1002 independent benchmarks$1.37 per solved taskModel BDeepSeek V4.1 FlashDeepSeek77.2/1002 independent benchmarksNo cost per solved task
- Shared results
- 61
- Claude Opus 4.5 only
- 44
- DeepSeek V4.1 Flash only
- 40
- Like-for-like categories
- 7 of 9
Shared results can support a head-to-head reading. Results only one model has describe coverage, not superiority.
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, four public coding benchmarks
DeepSeek V4.1 Flash
DeepSeek V4.1 Flash scores 77.2 against 66.8.
2 benchmarks behind each score
Intelligence
AA Intelligence Index
Claude Opus 4.5
Claude Opus 4.5 leads, 29.1 against 24.7.
Same board, both measured
Reasoning
GPQA Diamond
No call
Only Claude Opus 4.5 has a GPQA Diamond result, 85.9%.
Directional only
Math
AIME
No call
Only Claude Opus 4.5 has a AIME result, 95.4%.
Directional only
Knowledge
MMLU Pro
No call
Only Claude Opus 4.5 has a MMLU Pro result, 87.3%.
Directional only
Web design
Design Arena: websites
DeepSeek V4.1 Flash
DeepSeek V4.1 Flash leads, 1309 against 1247.
Same board, both measured
Long documents
Listed context window
DeepSeek V4.1 Flash
DeepSeek V4.1 Flash takes 1.05M tokens against 200K.
Listed by OpenRouter
Everyday cost
1K input + 500 output tokens
DeepSeek V4.1 Flash
Claude Opus 4.5 $0.018, DeepSeek V4.1 Flash $0.0003 per turn.
List prices
Cost per solved task
One SWE-bench Verified task, solved
No call
Only Claude Opus 4.5 has the number, $1.37.
Directional only
At a glance
- Coding index
- Claude Opus 4.5 66.8 from 2 benchmarks, DeepSeek V4.1 Flash 77.2 from 2 benchmarks.
- Widest category
- Coding, 19.9 points apart on average over 6 shared benchmarks.
- Widest single gap
- Vibe Code Bench (Vals AI): Claude Opus 4.5 20.6% against DeepSeek V4.1 Flash 84.7%, 64.1 points apart on a 0 to 100 scale.
- Output price
- Claude Opus 4.5 $25.00 against DeepSeek V4.1 Flash $0.525 per million output tokens, 47.6x apart.
- Context window
- Claude Opus 4.5 takes 200K 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 Opus 4.5 | Bars | DeepSeek V4.1 Flash | Ties |
|---|---|---|---|---|
| Coding | 1 | 5 | ||
| Intelligence | 1 | 1 | ||
| Reasoning | 0 | 9 | ||
| Math | 0 | 6 | ||
| Knowledge | 4 | 3 | ||
| Web design | 0 | 8 | ||
| General | 7 | 15 | 1 tie | |
| All shared boards | 13 | 47 | 1 tie |
CodingLike-for-likeFour of these boards feed the Vibe Coding Index15
| Benchmark | Claude Opus 4.5 | DeepSeek V4.1 Flash | Leader |
|---|---|---|---|
| SWE-bench Verified | 79.2% | Not measured | Only Claude Opus 4.5 measured |
| SWE-bench (full test set) | 52.6% | Not measured | Only Claude Opus 4.5 measured |
| SWE-bench Multilingual | 70.7% | Not measured | Only Claude Opus 4.5 measured |
| LiveBench coding | Not measured | 90.2% | Only DeepSeek V4.1 Flash measured |
| LMArena WebDev | 1494 | 1618 | DeepSeek V4.1 Flash |
| LiveCodeBench (Vals AI) | 83.7% | Not measured | Only Claude Opus 4.5 measured |
| SWE-bench Verified (Vals AI) | 76.4% | Not measured | Only Claude Opus 4.5 measured |
| Terminal-Bench 4 (Vals AI) | Not measured | 19.7% | Only DeepSeek V4.1 Flash measured |
| Vibe Code Bench (Vals AI) | 20.6% | 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 |
| LiveCodeBench (Artificial Analysis run) | 87.1% | Not measured | Only Claude Opus 4.5 measured |
| SciCode | Not measured | 51.9% | Only DeepSeek V4.1 Flash measured |
| Terminal-Bench Hard (Artificial Analysis run) | 47.0% | Not measured | Only Claude Opus 4.5 measured |
| Terminal-Bench | 63.1% | Not measured | Only Claude Opus 4.5 measured |
| FrontierCode | Not measured | 43.9% | Only DeepSeek V4.1 Flash measured |
| GSO-Bench | 26.5% | Not measured | Only Claude Opus 4.5 measured |
| WeirdML | 63.7% | Not measured | Only Claude Opus 4.5 measured |
| Cybench | 82.0% | Not measured | Only Claude Opus 4.5 measured |
| ALE-Bench | Not measured | 1092.3 | Only DeepSeek V4.1 Flash measured |
| LMArena Text: coding | 1503 | 1502 | Claude Opus 4.5 |
| LMArena Text: software and IT | 1483 | 1496 | DeepSeek V4.1 Flash |
| LMArena WebDev: React | 1478 | 1628 | DeepSeek V4.1 Flash |
| LMArena WebDev: HTML | 1510 | 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 7 boards here | |||
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index11
| Benchmark | Claude Opus 4.5 | DeepSeek V4.1 Flash | Leader |
|---|---|---|---|
| AA Intelligence Index | 29.1 | 24.7 | Claude Opus 4.5 |
| Epoch Capabilities Index | 150.1 | 155.9 | DeepSeek V4.1 Flash |
Agentic workDirectional onlyPublic boards, shown as published, kept out of the index24 boards, none shared
| Benchmark | Claude Opus 4.5 | DeepSeek V4.1 Flash | Leader |
|---|---|---|---|
| Design Arena: agents building web apps | 1159 | Not measured | Only Claude Opus 4.5 measured |
| Design Arena: agents building full-stack apps | 1156 | Not measured | Only Claude Opus 4.5 measured |
| Design Arena: agents building mobile apps | 1189 | Not measured | Only Claude Opus 4.5 measured |
| Design Arena: agents building Android apps | 1181 | Not measured | Only Claude Opus 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 |
| τ²-Bench Telecom | 89.5% | Not measured | Only Claude Opus 4.5 measured |
| APEX-Agents | Not measured | 39.5% | Only DeepSeek V4.1 Flash measured |
| METR time horizons | 75.0% | Not measured | Only Claude Opus 4.5 measured |
| Remote Labor Index | 3.8% | Not measured | Only Claude Opus 4.5 measured |
| GDPval | 45.5% | Not measured | Only Claude Opus 4.5 measured |
| BALROG | 43.5% | Not measured | Only Claude Opus 4.5 measured |
| DeepResearch Bench | 54.8% | Not measured | Only Claude Opus 4.5 measured |
| OSWorld | 66.3% | Not measured | Only Claude Opus 4.5 measured |
| Vending-Bench 2 | $4,967 | Not measured | Only Claude Opus 4.5 measured |
| Neither model has a result on the other 15 boards here | |||
ReasoningLike-for-likePublic boards, shown as published, kept out of the index09
| Benchmark | Claude Opus 4.5 | DeepSeek V4.1 Flash | Leader |
|---|---|---|---|
| GPQA Diamond | 85.9% | Not measured | Only Claude Opus 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) | 83.0% | Not measured | Only Claude Opus 4.5 measured |
| GPQA Diamond (Artificial Analysis run) | 86.6% | Not measured | Only Claude Opus 4.5 measured |
| Humanity's Last Exam (Artificial Analysis run) | 30.1% | 39.2% | DeepSeek V4.1 Flash |
| GPQA Diamond (Epoch AI run) | 86.0% | 89.8% | DeepSeek V4.1 Flash |
| ARC-AGI | 80.0% | 94.5% | DeepSeek V4.1 Flash |
| ARC-AGI-2 | 37.6% | 72.9% | DeepSeek V4.1 Flash |
| SimpleBench | 62.0% | Not measured | Only Claude Opus 4.5 measured |
| Chess puzzles | 14.0% | 48.0% | DeepSeek V4.1 Flash |
| Mystery game puzzles | 22.0% | 43.0% | DeepSeek V4.1 Flash |
| EBR-bench | 14.3% | Not measured | Only Claude Opus 4.5 measured |
| VPCT | 40.0% | Not measured | Only Claude Opus 4.5 measured |
| LMArena Text: hard prompts | 1476 | 1483 | DeepSeek V4.1 Flash |
| LMArena Text: expert | 1487 | 1501 | DeepSeek V4.1 Flash |
| LMArena Text: hard prompts in English | 1482 | 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 |
| Neither model has a result on the other 2 boards here | |||
MathLike-for-likePublic boards, shown as published, kept out of the index06
| Benchmark | Claude Opus 4.5 | DeepSeek V4.1 Flash | Leader |
|---|---|---|---|
| AIME | 95.4% | Not measured | Only Claude Opus 4.5 measured |
| MGSM (Vals AI) | 95.2% | Not measured | Only Claude Opus 4.5 measured |
| AA Math Index | 91.3 | Not measured | Only Claude Opus 4.5 measured |
| AIME 2025 (Artificial Analysis run) | 91.3% | Not measured | Only Claude Opus 4.5 measured |
| OTIS Mock AIME | 86.1% | 98.3% | DeepSeek V4.1 Flash |
| FrontierMath, tiers 1 to 3 | 34.4% | 67.4% | DeepSeek V4.1 Flash |
| FrontierMath, tier 4 | 4.9% | 26.8% | DeepSeek V4.1 Flash |
| ProofBench | 36.0% | 54.0% | DeepSeek V4.1 Flash |
| LMArena Text: math | 1463 | 1478 | DeepSeek V4.1 Flash |
| LMArena Text: mathematical work | 1468 | 1485 | DeepSeek V4.1 Flash |
| Neither model has a result on the other 3 boards here | |||
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index43
| Benchmark | Claude Opus 4.5 | DeepSeek V4.1 Flash | Leader |
|---|---|---|---|
| MMLU Pro | 87.3% | Not measured | Only Claude Opus 4.5 measured |
| LegalBench (Vals AI) | 84.6% | 83.3% | Claude Opus 4.5 |
| CaseLaw (Vals AI) | 62.6% | Not measured | Only Claude Opus 4.5 measured |
| CorpFin (Vals AI) | 65.1% | Not measured | Only Claude Opus 4.5 measured |
| TaxEval (Vals AI) | 74.9% | Not measured | Only Claude Opus 4.5 measured |
| MortgageTax (Vals AI) | 68.7% | Not measured | Only Claude Opus 4.5 measured |
| MedQA (Vals AI) | 95.9% | Not measured | Only Claude Opus 4.5 measured |
| MedCode (Vals AI) | 49.2% | 41.2% | Claude Opus 4.5 |
| MMLU Pro (Artificial Analysis run) | 89.5% | Not measured | Only Claude Opus 4.5 measured |
| SimpleQA Verified | 45.7% | 42.9% | Claude Opus 4.5 |
| GeoBench | 75.0% | Not measured | Only Claude Opus 4.5 measured |
| LMArena Text: science | 1454 | 1469 | DeepSeek V4.1 Flash |
| LMArena Text: medicine and healthcare | 1444 | 1484 | DeepSeek V4.1 Flash |
| LMArena Text: legal and government | 1459 | 1443 | Claude Opus 4.5 |
| LMArena Text: business and finance | 1448 | 1461 | DeepSeek V4.1 Flash |
| Neither model has a result on the other 2 boards here | |||
Web designLike-for-likePublic boards, shown as published, kept out of the index08
| Benchmark | Claude Opus 4.5 | DeepSeek V4.1 Flash | Leader |
|---|---|---|---|
| Design Arena: websites | 1247 | 1309 | DeepSeek V4.1 Flash |
| Design Arena: UI components | 1238 | 1314 | DeepSeek V4.1 Flash |
| Design Arena: game dev | 1229 | 1331 | DeepSeek V4.1 Flash |
| Design Arena: data viz | 1243 | 1290 | DeepSeek V4.1 Flash |
| Design Arena: 3D | 1214 | 1356 | DeepSeek V4.1 Flash |
| Design Arena: all code categories | 1242 | 1320 | DeepSeek V4.1 Flash |
| Design Arena: SVG | 1180 | 1243 | DeepSeek V4.1 Flash |
| Design Arena: ASCII art | 1190 | 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 index715
| Benchmark | Claude Opus 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) | 52.1% | 47.9% | Claude Opus 4.5 |
| MedScribe (Vals AI) | 85.3% | 85.5% | DeepSeek V4.1 Flash |
| IFBench | 58.0% | Not measured | Only Claude Opus 4.5 measured |
| Long context reasoning (AA-LCR) | 77.3% | 84.0% | DeepSeek V4.1 Flash |
| DTBench | 89.9% | 89.9% | Tie |
| LMCA | 44.5% | 47.0% | DeepSeek V4.1 Flash |
| CL-bench | 21.1% | Not measured | Only Claude Opus 4.5 measured |
| Surface Evolver Bench | Not measured | 46.3% | Only DeepSeek V4.1 Flash measured |
| Furniture assembly | 28.3% | 34.2% | DeepSeek V4.1 Flash |
| LMArena Text | 1451 | 1464 | DeepSeek V4.1 Flash |
| LMArena Text: instruction following | 1478 | 1473 | Claude Opus 4.5 |
| LMArena Text: creative writing | 1445 | 1437 | Claude Opus 4.5 |
| LMArena Vision | Not measured | 1278 | Only DeepSeek V4.1 Flash measured |
| LMArena Text: English | 1461 | 1473 | DeepSeek V4.1 Flash |
| LMArena Text: non-English | 1438 | 1449 | DeepSeek V4.1 Flash |
| LMArena Text: Chinese | 1470 | 1501 | DeepSeek V4.1 Flash |
| LMArena Text: German | 1449 | 1470 | DeepSeek V4.1 Flash |
| LMArena Text: Japanese | 1417 | 1432 | DeepSeek V4.1 Flash |
| LMArena Text: Korean | 1424 | 1436 | DeepSeek V4.1 Flash |
| LMArena Text: French | 1471 | 1465 | Claude Opus 4.5 |
| LMArena Text: Spanish | 1457 | 1459 | DeepSeek V4.1 Flash |
| LMArena Text: Russian | 1447 | 1467 | DeepSeek V4.1 Flash |
| LMArena Text: Polish | 1439 | 1457 | DeepSeek V4.1 Flash |
| LMArena Text: multi-turn | 1466 | 1461 | Claude Opus 4.5 |
| LMArena Text: longer queries | 1479 | 1473 | Claude Opus 4.5 |
| LMArena Text: writing and language | 1452 | 1450 | Claude Opus 4.5 |
| LMArena Text: entertainment and media | 1434 | 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 | 1462 | Not measured | Only Claude Opus 4.5 measured |
| Neither model has a result on the other 11 boards here | |||
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
| Benchmark | Claude Opus 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 Opus 4.5$0.018Fits in one request
DeepSeek V4.1 Flash$0.0003Fits in one request
DeepSeek V4.1 Flash costs less
Repository review
50K input + 3K output tokens
Claude Opus 4.5$0.325Fits in one request
DeepSeek V4.1 Flash$0.0040Fits in one request
DeepSeek V4.1 Flash costs less
Agent loop
200K input + 10K output tokens
Claude Opus 4.5$1.25Exceeds the context window
DeepSeek V4.1 Flash$0.015Fits 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 Opus 4.5 | DeepSeek V4.1 Flash |
|---|---|---|
| Maker | Anthropic | DeepSeek |
| Weights | No public weights listed | Open weights |
| Released | November 24, 2025 | September 10, 2026 |
| Context window | 200K | 1.05M |
| Input $/Mtok | $5.00 | $0.049 |
| Output $/Mtok | $25.00 | $0.525 |
| Coding index | 66.8 | 77.2 |
| Independent measurements behind it | 2 | 2 |
| Cost per solved task | $1.37 | Not computable |
| Source | OpenRouter listing | OpenRouter listing |
Questions
Is Claude Opus 4.5 better than DeepSeek V4.1 Flash for coding?
Pick DeepSeek V4.1 Flash for coding: it scores 77.2 on the Vibe Coding Index against 66.8 for Claude Opus 4.5. Pick Claude Opus 4.5 when what matters is LMArena Text: coding or AA Intelligence Index, where it leads.
Which is cheaper, Claude Opus 4.5 or DeepSeek V4.1 Flash?
Claude Opus 4.5 costs $5.00 per million input tokens and $25.00 per million output tokens; DeepSeek V4.1 Flash costs $0.049 and $0.525. Cost per solved task is known for Claude Opus 4.5 only.
Which has the bigger context window, Claude Opus 4.5 or DeepSeek V4.1 Flash?
DeepSeek V4.1 Flash, with 1.05M tokens against 200K.
How many benchmarks is the Claude Opus 4.5 vs DeepSeek V4.1 Flash comparison based on?
61 benchmarks have a result for both models as of October 21, 2026. Claude Opus 4.5's coding index rests on 2 independent benchmarks and DeepSeek V4.1 Flash's on 2. Where only one model has a result, the page says so instead of naming a winner.