GPT-5.1 vs Qwen3.5 Plus 2026-04-20
GPT-5.1 leads Qwen3.5 Plus 2026-04-20 on coding, 40.4 to 39.5 on the Vibe Coding Index, and Qwen3.5 Plus 2026-04-20 costs 5.6x less per output token ($1.80 vs $10.00 per million). Updated October 22, 2026; 24 benchmarks have a result for both.
GPT-5.1 or Qwen3.5 Plus 2026-04-20: which to pick
GPT-5.1 and Qwen3.5 Plus 2026-04-20 are level for coding, 40.4 against 39.5 on the Vibe Coding Index, so price and context decide.
Pick Qwen3.5 Plus 2026-04-20 for output tokens 5.6x cheaper ($1.80 vs $10.00 per million) and a larger context window (1M against 400K tokens). Pick GPT-5.1 for a lower cost per solved task ($1.02 against $1.35) and work measured by LiveCodeBench (Vals AI) or Vibe Code Bench (Vals AI), where it leads.
- Shared results
- 24
- GPT-5.1 only
- 82
- Qwen3.5 Plus 2026-04-20 only
- 1
- 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
No call
Level: 40.4 against 39.5, inside 2 points.
3 and 2 benchmarks behind the scores
Intelligence
AA Intelligence Index
No call
Only GPT-5.1 has a AA Intelligence Index result, 24.7.
Directional only
Reasoning
GPQA Diamond
Qwen3.5 Plus 2026-04-20
Qwen3.5 Plus 2026-04-20 leads, 87.4% against 86.6%.
Same board, both measured
Math
AIME
GPT-5.1
GPT-5.1 leads, 93.3% against 86.0%.
Same board, both measured
Knowledge
MMLU Pro
Qwen3.5 Plus 2026-04-20
Qwen3.5 Plus 2026-04-20 leads, 87.2% against 86.4%.
Same board, both measured
Web design
Design Arena: websites
No call
Only GPT-5.1 has a Design Arena: websites result, 1187.
Directional only
Long documents
Listed context window
Qwen3.5 Plus 2026-04-20
Qwen3.5 Plus 2026-04-20 takes 1M tokens against 400K.
Listed by OpenRouter
Everyday cost
1K input + 500 output tokens
Qwen3.5 Plus 2026-04-20
GPT-5.1 $0.0063, Qwen3.5 Plus 2026-04-20 $0.0012 per turn.
List prices
Cost per solved task
One SWE-bench Verified task, solved
GPT-5.1
GPT-5.1 $1.02, Qwen3.5 Plus 2026-04-20 $1.35.
Published attempt cost and pass rate
At a glance
- Coding index
- GPT-5.1 40.4 from 3 benchmarks, Qwen3.5 Plus 2026-04-20 39.5 from 2 benchmarks.
- Widest category
- Reasoning, 20.0 points apart on average over 5 shared benchmarks.
- Widest single gap
- MMMU Pro (Vals AI): GPT-5.1 83.2% against Qwen3.5 Plus 2026-04-20 22.8%, 60.4 points apart on a 0 to 100 scale.
- Output price
- GPT-5.1 $10.00 against Qwen3.5 Plus 2026-04-20 $1.80 per million output tokens, 5.6x apart.
- Context window
- GPT-5.1 takes 400K tokens, Qwen3.5 Plus 2026-04-20 1M.
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 | GPT-5.1 | Bars | Qwen3.5 Plus 2026-04-20 | Ties |
|---|---|---|---|---|
| Coding | 2 | 1 | ||
| Intelligence | 1 | 0 | ||
| Agentic work | 1 | 0 | ||
| Reasoning | 4 | 1 | ||
| Math | 2 | 0 | ||
| Knowledge | 5 | 2 | ||
| General | 5 | 0 | ||
| All shared boards | 20 | 4 |
CodingLike-for-likeSix of these boards feed the Vibe Coding Index21
| Benchmark | GPT-5.1 | Qwen3.5 Plus 2026-04-20 | Leader |
|---|---|---|---|
| SWE-bench Verified | 66.0% | Not measured | Only GPT-5.1 measured |
| LMArena WebDev | 1396 | Not measured | Only GPT-5.1 measured |
| AA Coding Index | 49.4 | Not measured | Only GPT-5.1 measured |
| LiveCodeBench (Vals AI) | 86.5% | 85.3% | GPT-5.1 |
| SWE-bench Verified (Vals AI) | 69.8% | 71.2% | Qwen3.5 Plus 2026-04-20 |
| Vibe Code Bench (Vals AI) | 24.6% | 15.7% | GPT-5.1 |
| LiveCodeBench (Artificial Analysis run) | 86.8% | Not measured | Only GPT-5.1 measured |
| Terminal-Bench Hard (Artificial Analysis run) | 45.5% | Not measured | Only GPT-5.1 measured |
| Terminal-Bench | 47.6% | Not measured | Only GPT-5.1 measured |
| GSO-Bench | 13.7% | Not measured | Only GPT-5.1 measured |
| WeirdML | 60.8% | Not measured | Only GPT-5.1 measured |
| ALE-Bench | Not measured | 608.9 | Only Qwen3.5 Plus 2026-04-20 measured |
| LMArena Text: coding | 1453 | Not measured | Only GPT-5.1 measured |
| LMArena Text: software and IT | 1454 | Not measured | Only GPT-5.1 measured |
| LMArena WebDev: React | 1307 | Not measured | Only GPT-5.1 measured |
| LMArena WebDev: HTML | 1405 | Not measured | Only GPT-5.1 measured |
| LMArena WebDev: from an image | 1421 | Not measured | Only GPT-5.1 measured |
| Neither model has a result on the other 26 boards here | |||
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index10
| Benchmark | GPT-5.1 | Qwen3.5 Plus 2026-04-20 | Leader |
|---|---|---|---|
| AA Intelligence Index | 24.7 | Not measured | Only GPT-5.1 measured |
| Epoch Capabilities Index | 149.8 | 146.2 | GPT-5.1 |
Agentic workLike-for-likePublic boards, shown as published, kept out of the index10
| Benchmark | GPT-5.1 | Qwen3.5 Plus 2026-04-20 | Leader |
|---|---|---|---|
| τ²-Bench Telecom | 81.9% | Not measured | Only GPT-5.1 measured |
| DeepResearch Bench | 42.8% | Not measured | Only GPT-5.1 measured |
| Vending-Bench 2 | $1,473 | $1 | GPT-5.1 |
| MCP Atlas | 50.1% | Not measured | Only GPT-5.1 measured |
| Neither model has a result on the other 38 boards here | |||
ReasoningLike-for-likePublic boards, shown as published, kept out of the index41
| Benchmark | GPT-5.1 | Qwen3.5 Plus 2026-04-20 | Leader |
|---|---|---|---|
| GPQA Diamond | 86.6% | 87.4% | Qwen3.5 Plus 2026-04-20 |
| MMMU Pro (Vals AI) | 83.2% | 22.8% | GPT-5.1 |
| GPQA Diamond (Artificial Analysis run) | 87.3% | Not measured | Only GPT-5.1 measured |
| Humanity's Last Exam (Artificial Analysis run) | 28.5% | Not measured | Only GPT-5.1 measured |
| GPQA Diamond (Epoch AI run) | 87.6% | 84.8% | GPT-5.1 |
| ARC-AGI | 72.8% | Not measured | Only GPT-5.1 measured |
| ARC-AGI-2 | 17.6% | Not measured | Only GPT-5.1 measured |
| SimpleBench | 53.2% | Not measured | Only GPT-5.1 measured |
| Chess puzzles | 42.0% | 8.0% | GPT-5.1 |
| Mystery game puzzles | 19.0% | 17.0% | GPT-5.1 |
| VPCT | 58.7% | Not measured | Only GPT-5.1 measured |
| LMArena Text: hard prompts | 1457 | Not measured | Only GPT-5.1 measured |
| LMArena Text: expert | 1470 | Not measured | Only GPT-5.1 measured |
| LMArena Text: hard prompts in English | 1462 | Not measured | Only GPT-5.1 measured |
| LMArena Vision: diagrams | 1264 | Not measured | Only GPT-5.1 measured |
| LMArena Vision: homework | 1272 | Not measured | Only GPT-5.1 measured |
| Neither model has a result on the other 7 boards here | |||
MathLike-for-likePublic boards, shown as published, kept out of the index20
| Benchmark | GPT-5.1 | Qwen3.5 Plus 2026-04-20 | Leader |
|---|---|---|---|
| AIME | 93.3% | 86.0% | GPT-5.1 |
| MGSM (Vals AI) | 93.0% | Not measured | Only GPT-5.1 measured |
| AA Math Index | 94.0 | Not measured | Only GPT-5.1 measured |
| AIME 2025 (Artificial Analysis run) | 94.0% | Not measured | Only GPT-5.1 measured |
| OTIS Mock AIME | 88.6% | 86.7% | GPT-5.1 |
| LMArena Text: math | 1446 | Not measured | Only GPT-5.1 measured |
| LMArena Text: mathematical work | 1449 | Not measured | Only GPT-5.1 measured |
| MathArena | 17.3% | Not measured | Only GPT-5.1 measured |
| Neither model has a result on the other 6 boards here | |||
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index52
| Benchmark | GPT-5.1 | Qwen3.5 Plus 2026-04-20 | Leader |
|---|---|---|---|
| MMLU Pro | 86.4% | 87.2% | Qwen3.5 Plus 2026-04-20 |
| LegalBench (Vals AI) | 85.7% | 85.1% | GPT-5.1 |
| CaseLaw (Vals AI) | 73.4% | 59.7% | GPT-5.1 |
| CorpFin (Vals AI) | 63.8% | 65.3% | Qwen3.5 Plus 2026-04-20 |
| TaxEval (Vals AI) | 74.9% | Not measured | Only GPT-5.1 measured |
| MortgageTax (Vals AI) | 61.4% | 60.8% | GPT-5.1 |
| MedQA (Vals AI) | 96.4% | 95.2% | GPT-5.1 |
| MedCode (Vals AI) | 52.7% | Not measured | Only GPT-5.1 measured |
| MMLU Pro (Artificial Analysis run) | 87.0% | Not measured | Only GPT-5.1 measured |
| SimpleQA Verified | 48.0% | 25.4% | GPT-5.1 |
| LMArena Text: science | 1459 | Not measured | Only GPT-5.1 measured |
| LMArena Text: medicine and healthcare | 1456 | Not measured | Only GPT-5.1 measured |
| LMArena Text: legal and government | 1459 | Not measured | Only GPT-5.1 measured |
| LMArena Text: business and finance | 1431 | Not measured | Only GPT-5.1 measured |
| FACTS Benchmark Suite | 45.0% | Not measured | Only GPT-5.1 measured |
| PRBench Finance | 48.0% | Not measured | Only GPT-5.1 measured |
| PRBench Legal | 49.3% | Not measured | Only GPT-5.1 measured |
| Neither model has a result on the other 3 boards here | |||
Web designDirectional onlyPublic boards, shown as published, kept out of the index8 boards, none shared
| Benchmark | GPT-5.1 | Qwen3.5 Plus 2026-04-20 | Leader |
|---|---|---|---|
| Design Arena: websites | 1187 | Not measured | Only GPT-5.1 measured |
| Design Arena: UI components | 1164 | Not measured | Only GPT-5.1 measured |
| Design Arena: game dev | 1178 | Not measured | Only GPT-5.1 measured |
| Design Arena: data viz | 1205 | Not measured | Only GPT-5.1 measured |
| Design Arena: 3D | 1060 | Not measured | Only GPT-5.1 measured |
| Design Arena: all code categories | 1170 | Not measured | Only GPT-5.1 measured |
| Design Arena: SVG | 1148 | Not measured | Only GPT-5.1 measured |
| Design Arena: ASCII art | 1118 | Not measured | Only GPT-5.1 measured |
| Neither model has a result on the other 1 board here | |||
GeneralLike-for-likePublic boards, shown as published, kept out of the index50
| Benchmark | GPT-5.1 | Qwen3.5 Plus 2026-04-20 | Leader |
|---|---|---|---|
| SAGE (Vals AI) | 43.2% | 30.4% | GPT-5.1 |
| MedScribe (Vals AI) | 88.1% | Not measured | Only GPT-5.1 measured |
| IFBench | 72.9% | Not measured | Only GPT-5.1 measured |
| Long context reasoning (AA-LCR) | 80.0% | Not measured | Only GPT-5.1 measured |
| DTBench | 90.1% | 80.5% | GPT-5.1 |
| LMCA | 43.9% | 36.4% | GPT-5.1 |
| CL-bench | 23.7% | 19.8% | GPT-5.1 |
| CL-bench Life | 17.3% | 12.4% | GPT-5.1 |
| LMArena Text | 1443 | Not measured | Only GPT-5.1 measured |
| LMArena Text: instruction following | 1443 | Not measured | Only GPT-5.1 measured |
| LMArena Text: creative writing | 1427 | Not measured | Only GPT-5.1 measured |
| LMArena Vision | 1250 | Not measured | Only GPT-5.1 measured |
| LMArena Text: English | 1451 | Not measured | Only GPT-5.1 measured |
| LMArena Text: non-English | 1431 | Not measured | Only GPT-5.1 measured |
| LMArena Text: Chinese | 1495 | Not measured | Only GPT-5.1 measured |
| LMArena Text: German | 1438 | Not measured | Only GPT-5.1 measured |
| LMArena Text: Japanese | 1453 | Not measured | Only GPT-5.1 measured |
| LMArena Text: Korean | 1401 | Not measured | Only GPT-5.1 measured |
| LMArena Text: French | 1450 | Not measured | Only GPT-5.1 measured |
| LMArena Text: Spanish | 1433 | Not measured | Only GPT-5.1 measured |
| LMArena Text: Russian | 1435 | Not measured | Only GPT-5.1 measured |
| LMArena Text: Polish | 1440 | Not measured | Only GPT-5.1 measured |
| LMArena Text: multi-turn | 1450 | Not measured | Only GPT-5.1 measured |
| LMArena Text: longer queries | 1448 | Not measured | Only GPT-5.1 measured |
| LMArena Text: writing and language | 1428 | Not measured | Only GPT-5.1 measured |
| LMArena Text: entertainment and media | 1415 | Not measured | Only GPT-5.1 measured |
| LMArena Vision: English | 1252 | Not measured | Only GPT-5.1 measured |
| LMArena Vision: Chinese | 1270 | Not measured | Only GPT-5.1 measured |
| LMArena Vision: reading text | 1255 | Not measured | Only GPT-5.1 measured |
| LMArena Vision: humor | 1263 | Not measured | Only GPT-5.1 measured |
| LMArena Vision: captioning | 1252 | Not measured | Only GPT-5.1 measured |
| LMArena Vision: recognizing things | 1232 | Not measured | Only GPT-5.1 measured |
| LMArena Vision: creative writing | 1266 | Not measured | Only GPT-5.1 measured |
| LMArena Document | 1403 | Not measured | Only GPT-5.1 measured |
| MultiChallenge | 63.4% | Not measured | Only GPT-5.1 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 | GPT-5.1 | Qwen3.5 Plus 2026-04-20 | 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 Plus 2026-04-20 costs less
Repository review
50K input + 3K output tokens
Qwen3.5 Plus 2026-04-20 costs less
Agent loop
200K input + 10K output tokens
Qwen3.5 Plus 2026-04-20 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 | OpenAI GPT-5.1 | Qwen3.5 Plus 2026-04-20 |
|---|---|---|
| Maker | OpenAI | Qwen |
| Weights | No public weights listed | No public weights listed |
| Released | November 13, 2025 | April 27, 2026 |
| Context window | 400K | 1M |
| Input $/Mtok | $1.25 | $0.30 |
| Output $/Mtok | $10.00 | $1.80 |
| Coding index | 40.4 | 39.5 |
| Independent measurements behind it | 3 | 2 |
| Cost per solved task | $1.02 | $1.35 |
| Source | OpenRouter listing | OpenRouter listing |
Questions
Is GPT-5.1 better than Qwen3.5 Plus 2026-04-20 for coding?
GPT-5.1 and Qwen3.5 Plus 2026-04-20 are level for coding, 40.4 against 39.5 on the Vibe Coding Index, so price and context decide. Pick Qwen3.5 Plus 2026-04-20 for output tokens 5.6x cheaper ($1.80 vs $10.00 per million) and a larger context window (1M against 400K tokens). Pick GPT-5.1 for a lower cost per solved task ($1.02 against $1.35) and work measured by LiveCodeBench (Vals AI) or Vibe Code Bench (Vals AI), where it leads.
Which is cheaper, GPT-5.1 or Qwen3.5 Plus 2026-04-20?
GPT-5.1 costs $1.25 per million input tokens and $10.00 per million output tokens; Qwen3.5 Plus 2026-04-20 costs $0.30 and $1.80. Per solved SWE-bench Verified task, GPT-5.1 costs $1.02 and Qwen3.5 Plus 2026-04-20 $1.35.
Which has the bigger context window, GPT-5.1 or Qwen3.5 Plus 2026-04-20?
Qwen3.5 Plus 2026-04-20, with 1M tokens against 400K.
How many benchmarks is the GPT-5.1 vs Qwen3.5 Plus 2026-04-20 comparison based on?
24 benchmarks have a result for both models as of October 22, 2026. GPT-5.1's coding index rests on 3 independent benchmarks and Qwen3.5 Plus 2026-04-20's on 2. Where only one model has a result, the page says so instead of naming a winner.