GPT-5.1 vs Qwen3.5-27B
Updated October 21, 2026. 52 benchmarks have a result for both. Coding is ranked on the Vibe Coding Index; every other board is shown as published.
Decision reading
Pick GPT-5.1 for coding: it scores 53.3 on the Vibe Coding Index against 22.6 for Qwen3.5-27B.
Pick Qwen3.5-27B when output tokens cost 4.6x less, or when what matters is LMArena WebDev: React or τ²-Bench Telecom, where it leads.
- Shared results
- 52
- GPT-5.1 only
- 48
- Qwen3.5-27B only
- 1
- 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
GPT-5.1
GPT-5.1 scores 53.3 against 22.6.
2 and 1 benchmarks behind the scores
Intelligence
AA Intelligence Index
GPT-5.1
GPT-5.1 leads, 24.7 against 22.9.
Same board, both measured
Reasoning
GPQA Diamond
No call
Only GPT-5.1 has a GPQA Diamond result, 86.6%.
Directional only
Math
AIME
No call
Only GPT-5.1 has a AIME result, 93.3%.
Directional only
Knowledge
MMLU Pro
No call
Only GPT-5.1 has a MMLU Pro result, 86.4%.
Directional only
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
GPT-5.1
GPT-5.1 takes 400K tokens against 262K.
Listed by OpenRouter
Everyday cost
1K input + 500 output tokens
Qwen3.5-27B
GPT-5.1 $0.0063, Qwen3.5-27B $0.0014 per turn.
List prices
Cost per solved task
One SWE-bench Verified task, solved
No call
Only GPT-5.1 has the number, $1.02.
Directional only
At a glance
- Coding index
- GPT-5.1 53.3 from 2 benchmarks, Qwen3.5-27B 22.6 from 1 benchmark.
- Widest category
- Agentic work, 10.0 points apart on average over 2 shared benchmarks.
- Widest single gap
- WeirdML: GPT-5.1 60.8% against Qwen3.5-27B 39.5%, 21.2 points apart on a 0 to 100 scale.
- Output price
- GPT-5.1 $10.00 against Qwen3.5-27B $2.16 per million output tokens, 4.6x apart.
- Context window
- GPT-5.1 takes 400K tokens, Qwen3.5-27B 262K.
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 | Qwen3.5-27B | Ties |
|---|---|---|---|---|
| Coding | 6 | 1 | ||
| Intelligence | 1 | 0 | ||
| Agentic work | 1 | 1 | ||
| Reasoning | 7 | 0 | ||
| Math | 2 | 0 | ||
| Knowledge | 4 | 0 | ||
| General | 27 | 2 | ||
| All shared boards | 48 | 4 |
CodingLike-for-likeFour of these boards feed the Vibe Coding Index61
| Benchmark | GPT-5.1 | Qwen3.5-27B | Leader |
|---|---|---|---|
| SWE-bench Verified | 66.0% | Not measured | Only GPT-5.1 measured |
| LMArena WebDev | 1396 | 1358 | GPT-5.1 |
| AA Coding Index | 49.4 | Not measured | Only GPT-5.1 measured |
| LiveCodeBench (Vals AI) | 86.5% | Not measured | Only GPT-5.1 measured |
| SWE-bench Verified (Vals AI) | 69.8% | Not measured | Only GPT-5.1 measured |
| Vibe Code Bench (Vals AI) | 24.6% | Not measured | Only GPT-5.1 measured |
| LiveCodeBench (Artificial Analysis run) | 86.8% | Not measured | Only GPT-5.1 measured |
| Terminal-Bench Hard (Artificial Analysis run) | 45.5% | 32.6% | GPT-5.1 |
| 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% | 39.5% | GPT-5.1 |
| ALE-Bench | Not measured | 349.4 | Only Qwen3.5-27B measured |
| LMArena Text: coding | 1453 | 1427 | GPT-5.1 |
| LMArena Text: software and IT | 1454 | 1431 | GPT-5.1 |
| LMArena WebDev: React | 1307 | 1346 | Qwen3.5-27B |
| LMArena WebDev: HTML | 1405 | 1386 | GPT-5.1 |
| LMArena WebDev: from an image | 1421 | Not measured | Only GPT-5.1 measured |
| Neither model has a result on the other 21 boards here | |||
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index10
| Benchmark | GPT-5.1 | Qwen3.5-27B | Leader |
|---|---|---|---|
| AA Intelligence Index | 24.7 | 22.9 | GPT-5.1 |
| Epoch Capabilities Index | 149.8 | Not measured | Only GPT-5.1 measured |
Agentic workLike-for-likePublic boards, shown as published, kept out of the index11
| Benchmark | GPT-5.1 | Qwen3.5-27B | Leader |
|---|---|---|---|
| τ²-Bench Telecom | 81.9% | 93.9% | Qwen3.5-27B |
| DeepResearch Bench | 42.8% | Not measured | Only GPT-5.1 measured |
| Vending-Bench 2 | $1,473 | $202 | GPT-5.1 |
| Neither model has a result on the other 36 boards here | |||
ReasoningLike-for-likePublic boards, shown as published, kept out of the index70
| Benchmark | GPT-5.1 | Qwen3.5-27B | Leader |
|---|---|---|---|
| GPQA Diamond | 86.6% | Not measured | Only GPT-5.1 measured |
| MMMU Pro (Vals AI) | 83.2% | Not measured | Only GPT-5.1 measured |
| GPQA Diamond (Artificial Analysis run) | 87.3% | 85.8% | GPT-5.1 |
| Humanity's Last Exam (Artificial Analysis run) | 28.5% | 23.9% | GPT-5.1 |
| GPQA Diamond (Epoch AI run) | 87.6% | Not measured | Only GPT-5.1 measured |
| 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% | Not measured | Only GPT-5.1 measured |
| Mystery game puzzles | 19.0% | Not measured | Only GPT-5.1 measured |
| VPCT | 58.7% | Not measured | Only GPT-5.1 measured |
| LMArena Text: hard prompts | 1457 | 1415 | GPT-5.1 |
| LMArena Text: expert | 1470 | 1427 | GPT-5.1 |
| LMArena Text: hard prompts in English | 1462 | 1429 | GPT-5.1 |
| LMArena Vision: diagrams | 1264 | 1249 | GPT-5.1 |
| LMArena Vision: homework | 1272 | 1256 | GPT-5.1 |
| Neither model has a result on the other 5 boards here | |||
MathLike-for-likePublic boards, shown as published, kept out of the index20
| Benchmark | GPT-5.1 | Qwen3.5-27B | Leader |
|---|---|---|---|
| AIME | 93.3% | Not measured | Only GPT-5.1 measured |
| 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% | Not measured | Only GPT-5.1 measured |
| LMArena Text: math | 1446 | 1429 | GPT-5.1 |
| LMArena Text: mathematical work | 1449 | 1429 | GPT-5.1 |
| Neither model has a result on the other 6 boards here | |||
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index40
| Benchmark | GPT-5.1 | Qwen3.5-27B | Leader |
|---|---|---|---|
| MMLU Pro | 86.4% | Not measured | Only GPT-5.1 measured |
| LegalBench (Vals AI) | 85.7% | Not measured | Only GPT-5.1 measured |
| CaseLaw (Vals AI) | 73.4% | Not measured | Only GPT-5.1 measured |
| CorpFin (Vals AI) | 63.8% | Not measured | Only GPT-5.1 measured |
| TaxEval (Vals AI) | 74.9% | Not measured | Only GPT-5.1 measured |
| MortgageTax (Vals AI) | 61.4% | Not measured | Only GPT-5.1 measured |
| MedQA (Vals AI) | 96.4% | Not measured | Only GPT-5.1 measured |
| 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% | Not measured | Only GPT-5.1 measured |
| LMArena Text: science | 1459 | 1437 | GPT-5.1 |
| LMArena Text: medicine and healthcare | 1456 | 1425 | GPT-5.1 |
| LMArena Text: legal and government | 1459 | 1405 | GPT-5.1 |
| LMArena Text: business and finance | 1431 | 1399 | GPT-5.1 |
| 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 | Qwen3.5-27B | Leader |
|---|---|---|---|
| Design Arena: websites | 1187 | Not measured | Only GPT-5.1 measured |
| Design Arena: UI components | 1166 | Not measured | Only GPT-5.1 measured |
| Design Arena: game dev | 1179 | Not measured | Only GPT-5.1 measured |
| Design Arena: data viz | 1204 | Not measured | Only GPT-5.1 measured |
| Design Arena: 3D | 1061 | Not measured | Only GPT-5.1 measured |
| Design Arena: all code categories | 1171 | Not measured | Only GPT-5.1 measured |
| Design Arena: SVG | 1149 | 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 index272
| Benchmark | GPT-5.1 | Qwen3.5-27B | Leader |
|---|---|---|---|
| SAGE (Vals AI) | 43.2% | Not measured | Only GPT-5.1 measured |
| MedScribe (Vals AI) | 88.1% | Not measured | Only GPT-5.1 measured |
| IFBench | 72.9% | 75.6% | Qwen3.5-27B |
| Long context reasoning (AA-LCR) | 80.0% | 77.7% | GPT-5.1 |
| DTBench | 90.1% | 82.4% | GPT-5.1 |
| LMCA | 43.9% | 34.0% | GPT-5.1 |
| CL-bench | 23.7% | Not measured | Only GPT-5.1 measured |
| CL-bench Life | 17.3% | Not measured | Only GPT-5.1 measured |
| LMArena Text | 1443 | 1409 | GPT-5.1 |
| LMArena Text: instruction following | 1443 | 1393 | GPT-5.1 |
| LMArena Text: creative writing | 1427 | 1362 | GPT-5.1 |
| LMArena Vision | 1250 | 1241 | GPT-5.1 |
| LMArena Text: English | 1451 | 1425 | GPT-5.1 |
| LMArena Text: non-English | 1431 | 1390 | GPT-5.1 |
| LMArena Text: Chinese | 1495 | 1478 | GPT-5.1 |
| LMArena Text: German | 1438 | 1392 | GPT-5.1 |
| LMArena Text: Japanese | 1453 | 1346 | GPT-5.1 |
| LMArena Text: Korean | 1401 | 1359 | GPT-5.1 |
| LMArena Text: French | 1450 | 1410 | GPT-5.1 |
| LMArena Text: Spanish | 1433 | 1407 | GPT-5.1 |
| LMArena Text: Russian | 1435 | 1390 | GPT-5.1 |
| LMArena Text: Polish | 1440 | 1375 | GPT-5.1 |
| LMArena Text: multi-turn | 1450 | 1410 | GPT-5.1 |
| LMArena Text: longer queries | 1448 | 1413 | GPT-5.1 |
| LMArena Text: writing and language | 1428 | 1380 | GPT-5.1 |
| LMArena Text: entertainment and media | 1415 | 1363 | GPT-5.1 |
| LMArena Vision: English | 1252 | 1246 | GPT-5.1 |
| LMArena Vision: Chinese | 1270 | 1301 | Qwen3.5-27B |
| LMArena Vision: reading text | 1255 | 1246 | GPT-5.1 |
| LMArena Vision: humor | 1263 | 1227 | GPT-5.1 |
| LMArena Vision: captioning | 1252 | 1170 | GPT-5.1 |
| LMArena Vision: recognizing things | 1232 | 1210 | GPT-5.1 |
| LMArena Vision: creative writing | 1266 | 1224 | GPT-5.1 |
| LMArena Document | 1403 | Not measured | Only GPT-5.1 measured |
| Neither model has a result on the other 12 boards here | |||
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
| Benchmark | GPT-5.1 | Qwen3.5-27B | 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
Qwen3.5-27B costs less
Repository review
50K input + 3K output tokens
Qwen3.5-27B costs less
Agent loop
200K input + 10K output tokens
Qwen3.5-27B 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 | Qwen3.5-27B |
|---|---|---|
| Maker | OpenAI | Qwen |
| Weights | No public weights listed | Open weights |
| Released | November 13, 2025 | February 25, 2026 |
| Context window | 400K | 262K |
| Input $/Mtok | $1.25 | $0.27 |
| Output $/Mtok | $10.00 | $2.16 |
| Coding index | 53.3 | 22.6 |
| Independent measurements behind it | 2 | 1 |
| Cost per solved task | $1.02 | Not computable |
| Source | OpenRouter listing | OpenRouter listing |
Questions
Is GPT-5.1 better than Qwen3.5-27B for coding?
Pick GPT-5.1 for coding: it scores 53.3 on the Vibe Coding Index against 22.6 for Qwen3.5-27B. Pick Qwen3.5-27B when output tokens cost 4.6x less, or when what matters is LMArena WebDev: React or τ²-Bench Telecom, where it leads.
Which is cheaper, GPT-5.1 or Qwen3.5-27B?
GPT-5.1 costs $1.25 per million input tokens and $10.00 per million output tokens; Qwen3.5-27B costs $0.27 and $2.16. Cost per solved task is known for GPT-5.1 only.
Which has the bigger context window, GPT-5.1 or Qwen3.5-27B?
GPT-5.1, with 400K tokens against 262K.
How many benchmarks is the GPT-5.1 vs Qwen3.5-27B comparison based on?
52 benchmarks have a result for both models as of October 21, 2026. GPT-5.1's coding index rests on 2 independent benchmarks and Qwen3.5-27B's on 1. Where only one model has a result, the page says so instead of naming a winner.