Claude Sonnet 4.5 vs Qwen3.5-Flash
Qwen3.5-Flash leads Claude Sonnet 4.5 on coding, 41.1 to 39.5 on the Vibe Coding Index, and Qwen3.5-Flash costs 57.7x less per output token ($0.26 vs $15.00 per million). Updated October 22, 2026; 54 benchmarks have a result for both.
Claude Sonnet 4.5 or Qwen3.5-Flash: which to pick
Claude Sonnet 4.5 and Qwen3.5-Flash are level for coding, 39.5 against 41.1 on the Vibe Coding Index, so price and context decide.
Pick Claude Sonnet 4.5 for work measured by LMArena WebDev or SWE-bench Verified (Vals AI), where it leads. Pick Qwen3.5-Flash for output tokens 57.7x cheaper ($0.26 vs $15.00 per million) and a lower cost per solved task ($0.40 against $1.16).
- Shared results
- 54
- Claude Sonnet 4.5 only
- 46
- Qwen3.5-Flash only
- 1
- Like-for-like categories
- 6 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
No call
Level: 39.5 against 41.1, inside 2 points.
3 and 2 benchmarks behind the scores
Intelligence
AA Intelligence Index
No call
Only Claude Sonnet 4.5 has a AA Intelligence Index result, 20.7.
Directional only
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
Qwen3.5-Flash
Qwen3.5-Flash leads, 82.8% against 81.6%.
Same board, both measured
Math
AIME
Qwen3.5-Flash
Qwen3.5-Flash leads, 92.5% against 88.2%.
Same board, both measured
Knowledge
MMLU Pro
Claude Sonnet 4.5
Claude Sonnet 4.5 leads, 87.4% against 84.1%.
Same board, both measured
Web design
Design Arena: websites
No call
Only Claude Sonnet 4.5 has a Design Arena: websites result, 1189.
Directional only
Long documents
Listed context window
No call
Both take 1M tokens.
Listed by OpenRouter
Everyday cost
1K input + 500 output tokens
Qwen3.5-Flash
Claude Sonnet 4.5 $0.011, Qwen3.5-Flash $0.0002 per turn.
List prices
Cost per solved task
One SWE-bench Verified task, solved
Qwen3.5-Flash
Claude Sonnet 4.5 $1.16, Qwen3.5-Flash $0.40.
Published attempt cost and pass rate
At a glance
- Coding index
- Claude Sonnet 4.5 39.5 from 3 benchmarks, Qwen3.5-Flash 41.1 from 2 benchmarks.
- Widest category
- Coding, 14.8 points apart on average over 7 shared benchmarks.
- Widest single gap
- LMArena WebDev: React: Claude Sonnet 4.5 1386 against Qwen3.5-Flash 1229, 26.1 points apart on a 0 to 100 scale.
- Output price
- Claude Sonnet 4.5 $15.00 against Qwen3.5-Flash $0.26 per million output tokens, 57.7x apart.
- Context window
- Both take 1M tokens.
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 | Qwen3.5-Flash | Ties |
|---|---|---|---|---|
| Coding | 6 | 1 | ||
| Intelligence | 1 | 0 | ||
| Reasoning | 3 | 4 | 1 tie | |
| Math | 3 | 2 | ||
| Knowledge | 9 | 3 | ||
| General | 20 | 1 | ||
| All shared boards | 42 | 11 | 1 tie |
CodingLike-for-likeSix of these boards feed the Vibe Coding Index61
| Benchmark | Claude Sonnet 4.5 | Qwen3.5-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 |
| LMArena WebDev | 1394 | 1244 | Claude Sonnet 4.5 |
| AA Coding Index | 52.1 | Not measured | Only Claude Sonnet 4.5 measured |
| LiveCodeBench (Vals AI) | 73.0% | 83.3% | Qwen3.5-Flash |
| SWE-bench Verified (Vals AI) | 70.0% | 64.4% | Claude Sonnet 4.5 |
| Vibe Code Bench (Vals AI) | 22.6% | Not measured | Only Claude Sonnet 4.5 measured |
| Terminal-Bench | 46.5% | Not measured | Only Claude Sonnet 4.5 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 | 265.9 | Only Qwen3.5-Flash measured |
| LMArena Text: coding | 1488 | 1412 | Claude Sonnet 4.5 |
| LMArena Text: software and IT | 1473 | 1416 | Claude Sonnet 4.5 |
| LMArena WebDev: React | 1386 | 1229 | Claude Sonnet 4.5 |
| LMArena WebDev: HTML | 1399 | 1291 | Claude Sonnet 4.5 |
| Neither model has a result on the other 27 boards here | |||
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index10
| Benchmark | Claude Sonnet 4.5 | Qwen3.5-Flash | Leader |
|---|---|---|---|
| AA Intelligence Index | 20.7 | Not measured | Only Claude Sonnet 4.5 measured |
| Epoch Capabilities Index | 146.7 | 143.5 | Claude Sonnet 4.5 |
Agentic workDirectional onlyPublic boards, shown as published, kept out of the index12 boards, none shared
| Benchmark | Claude Sonnet 4.5 | Qwen3.5-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 | 1136 | Not measured | Only Claude Sonnet 4.5 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 |
| MCP Atlas | 59.5% | Not measured | Only Claude Sonnet 4.5 measured |
| Neither model has a result on the other 30 boards here | |||
ReasoningLike-for-likePublic boards, shown as published, kept out of the index34
| Benchmark | Claude Sonnet 4.5 | Qwen3.5-Flash | Leader |
|---|---|---|---|
| GPQA Diamond | 81.6% | 82.8% | Qwen3.5-Flash |
| MMMU Pro (Vals AI) | 79.3% | 81.9% | Qwen3.5-Flash |
| GPQA Diamond (Epoch AI run) | 82.3% | 82.3% | Tie |
| ARC-AGI | 63.7% | Not measured | Only Claude Sonnet 4.5 measured |
| ARC-AGI-2 | 13.6% | Not measured | Only Claude Sonnet 4.5 measured |
| SimpleBench | 54.3% | Not measured | Only Claude Sonnet 4.5 measured |
| Chess puzzles | 10.0% | 14.0% | Qwen3.5-Flash |
| Mystery game puzzles | 17.0% | 20.0% | Qwen3.5-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 | 1403 | Claude Sonnet 4.5 |
| LMArena Text: expert | 1483 | 1407 | Claude Sonnet 4.5 |
| LMArena Text: hard prompts in English | 1471 | 1409 | Claude Sonnet 4.5 |
| Kagi LLM Benchmark | 57.9% | Not measured | Only Claude Sonnet 4.5 measured |
| Neither model has a result on the other 9 boards here | |||
MathLike-for-likePublic boards, shown as published, kept out of the index32
| Benchmark | Claude Sonnet 4.5 | Qwen3.5-Flash | Leader |
|---|---|---|---|
| AIME | 88.2% | 92.5% | Qwen3.5-Flash |
| MGSM (Vals AI) | 94.3% | Not measured | Only Claude Sonnet 4.5 measured |
| OTIS Mock AIME | 77.8% | 84.4% | Qwen3.5-Flash |
| FrontierMath, tiers 1 to 3 | 23.9% | 18.2% | Claude Sonnet 4.5 |
| FrontierMath, tier 4 | 2.4% | Not measured | Only Claude Sonnet 4.5 measured |
| ProofBench | 19.0% | Not measured | Only Claude Sonnet 4.5 measured |
| MATH level 5 | 97.7% | Not measured | Only Claude Sonnet 4.5 measured |
| LMArena Text: math | 1449 | 1407 | Claude Sonnet 4.5 |
| LMArena Text: mathematical work | 1462 | 1413 | Claude Sonnet 4.5 |
| MathArena | 12.6% | Not measured | Only Claude Sonnet 4.5 measured |
| Neither model has a result on the other 4 boards here | |||
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index93
| Benchmark | Claude Sonnet 4.5 | Qwen3.5-Flash | Leader |
|---|---|---|---|
| MMLU Pro | 87.4% | 84.1% | Claude Sonnet 4.5 |
| LegalBench (Vals AI) | 84.1% | 84.3% | Qwen3.5-Flash |
| CaseLaw (Vals AI) | 62.2% | 56.0% | Claude Sonnet 4.5 |
| CorpFin (Vals AI) | 62.0% | 63.6% | Qwen3.5-Flash |
| TaxEval (Vals AI) | 73.3% | 72.2% | Claude Sonnet 4.5 |
| MortgageTax (Vals AI) | 64.0% | 67.4% | Qwen3.5-Flash |
| MedQA (Vals AI) | 94.7% | Not measured | Only Claude Sonnet 4.5 measured |
| MedCode (Vals AI) | 44.1% | 33.0% | Claude Sonnet 4.5 |
| SimpleQA Verified | 30.7% | 20.3% | Claude Sonnet 4.5 |
| LMArena Text: science | 1448 | 1415 | Claude Sonnet 4.5 |
| LMArena Text: medicine and healthcare | 1444 | 1407 | Claude Sonnet 4.5 |
| LMArena Text: legal and government | 1451 | 1398 | Claude Sonnet 4.5 |
| LMArena Text: business and finance | 1440 | 1394 | Claude Sonnet 4.5 |
| FACTS Benchmark Suite | 40.6% | Not measured | Only Claude Sonnet 4.5 measured |
| PRBench Finance | 43.8% | Not measured | Only Claude Sonnet 4.5 measured |
| PRBench Legal | 40.8% | Not measured | Only Claude Sonnet 4.5 measured |
| Neither model has a result on the other 4 boards here | |||
Web designDirectional onlyPublic boards, shown as published, kept out of the index8 boards, none shared
| Benchmark | Claude Sonnet 4.5 | Qwen3.5-Flash | Leader |
|---|---|---|---|
| Design Arena: websites | 1189 | Not measured | Only Claude Sonnet 4.5 measured |
| Design Arena: UI components | 1170 | Not measured | Only Claude Sonnet 4.5 measured |
| Design Arena: game dev | 1166 | Not measured | Only Claude Sonnet 4.5 measured |
| Design Arena: data viz | 1167 | Not measured | Only Claude Sonnet 4.5 measured |
| Design Arena: 3D | 1157 | Not measured | Only Claude Sonnet 4.5 measured |
| Design Arena: all code categories | 1182 | Not measured | Only Claude Sonnet 4.5 measured |
| Design Arena: SVG | 1114 | Not measured | Only Claude Sonnet 4.5 measured |
| Design Arena: ASCII art | 1205 | Not measured | Only Claude Sonnet 4.5 measured |
| Neither model has a result on the other 1 board here | |||
GeneralLike-for-likePublic boards, shown as published, kept out of the index201
| Benchmark | Claude Sonnet 4.5 | Qwen3.5-Flash | Leader |
|---|---|---|---|
| SAGE (Vals AI) | 36.1% | 42.5% | Qwen3.5-Flash |
| MedScribe (Vals AI) | 84.5% | 70.6% | Claude Sonnet 4.5 |
| DTBench | 83.2% | 82.9% | Claude Sonnet 4.5 |
| LMCA | 38.8% | 29.1% | Claude Sonnet 4.5 |
| LMArena Text | 1438 | 1397 | Claude Sonnet 4.5 |
| LMArena Text: instruction following | 1459 | 1374 | Claude Sonnet 4.5 |
| LMArena Text: creative writing | 1442 | 1343 | Claude Sonnet 4.5 |
| LMArena Text: English | 1450 | 1404 | Claude Sonnet 4.5 |
| LMArena Text: non-English | 1425 | 1385 | Claude Sonnet 4.5 |
| LMArena Text: Chinese | 1460 | 1445 | Claude Sonnet 4.5 |
| LMArena Text: German | 1427 | 1390 | Claude Sonnet 4.5 |
| LMArena Text: Japanese | 1390 | 1369 | Claude Sonnet 4.5 |
| LMArena Text: Korean | 1402 | 1344 | Claude Sonnet 4.5 |
| LMArena Text: French | 1459 | 1413 | Claude Sonnet 4.5 |
| LMArena Text: Spanish | 1458 | 1400 | Claude Sonnet 4.5 |
| LMArena Text: Russian | 1437 | 1380 | Claude Sonnet 4.5 |
| LMArena Text: Polish | 1423 | 1376 | Claude Sonnet 4.5 |
| LMArena Text: multi-turn | 1465 | 1393 | Claude Sonnet 4.5 |
| LMArena Text: longer queries | 1475 | 1392 | Claude Sonnet 4.5 |
| LMArena Text: writing and language | 1442 | 1369 | Claude Sonnet 4.5 |
| LMArena Text: entertainment and media | 1428 | 1347 | Claude Sonnet 4.5 |
| LMArena Document | 1450 | Not measured | Only Claude Sonnet 4.5 measured |
| MultiChallenge | 55.3% | Not measured | Only Claude Sonnet 4.5 measured |
| Neither model has a result on the other 25 boards here | |||
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
| Benchmark | Claude Sonnet 4.5 | Qwen3.5-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
Qwen3.5-Flash costs less
Repository review
50K input + 3K output tokens
Qwen3.5-Flash costs less
Agent loop
200K input + 10K output tokens
Qwen3.5-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 | Qwen3.5-Flash |
|---|---|---|
| Maker | Anthropic | Qwen |
| Weights | No public weights listed | No public weights listed |
| Released | September 29, 2025 | February 25, 2026 |
| Context window | 1M | 1M |
| Input $/Mtok | $3.00 | $0.065 |
| Output $/Mtok | $15.00 | $0.26 |
| Coding index | 39.5 | 41.1 |
| Independent measurements behind it | 3 | 2 |
| Cost per solved task | $1.16 | $0.40 |
| Source | OpenRouter listing | OpenRouter listing |
Questions
Is Claude Sonnet 4.5 better than Qwen3.5-Flash for coding?
Claude Sonnet 4.5 and Qwen3.5-Flash are level for coding, 39.5 against 41.1 on the Vibe Coding Index, so price and context decide. Pick Claude Sonnet 4.5 for work measured by LMArena WebDev or SWE-bench Verified (Vals AI), where it leads. Pick Qwen3.5-Flash for output tokens 57.7x cheaper ($0.26 vs $15.00 per million) and a lower cost per solved task ($0.40 against $1.16).
Which is cheaper, Claude Sonnet 4.5 or Qwen3.5-Flash?
Claude Sonnet 4.5 costs $3.00 per million input tokens and $15.00 per million output tokens; Qwen3.5-Flash costs $0.065 and $0.26. Per solved SWE-bench Verified task, Claude Sonnet 4.5 costs $1.16 and Qwen3.5-Flash $0.40.
Which has the bigger context window, Claude Sonnet 4.5 or Qwen3.5-Flash?
Neither: both take 1M tokens.
How many benchmarks is the Claude Sonnet 4.5 vs Qwen3.5-Flash comparison based on?
54 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 Qwen3.5-Flash's on 2. Where only one model has a result, the page says so instead of naming a winner.