Claude Fable 5.1 vs gpt-oss-120b
Claude Fable 5.1 leads gpt-oss-120b on the Artificial Analysis Intelligence Index, 53.4 to 11.6, and gpt-oss-120b costs 100.0x less per output token ($0.50 vs $50.00 per million). Updated October 22, 2026; 55 benchmarks have a result for both.
vs boards won of 55 shared
Claude Fable 5.1 or gpt-oss-120b: which to pick
Only Claude Fable 5.1 has a coding score, 84.2 on the Vibe Coding Index; gpt-oss-120b has none, so the two cannot be ranked on coding.
Pick gpt-oss-120b for output tokens 100.0x cheaper ($0.50 vs $50.00 per million).
Model AClaude Fable 5.1Anthropic84.2/1005 independent benchmarksNo cost per solved taskModel Bgpt-oss-120bOpenAINot benchmarked1 independent benchmark$0.51 per solved task
- Shared results
- 55
- Claude Fable 5.1 only
- 69
- gpt-oss-120b only
- 26
- Like-for-like categories
- 8 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
Only Claude Fable 5.1 has a coding score, so no call is made.
One side not measured
Intelligence
AA Intelligence Index
Claude Fable 5.1
Claude Fable 5.1 leads, 53.4 against 11.6.
Same board, both measured
Agentic work
AA Agentic Index
Claude Fable 5.1
Claude Fable 5.1 leads, 57.9 against 3.7.
Same board, both measured
Reasoning
GPQA Diamond
Claude Fable 5.1
Claude Fable 5.1 leads, 93.4% against 78.5%.
Same board, both measured
Math
AIME
No call
Only gpt-oss-120b has a AIME result, 92.6%.
Directional only
Knowledge
MMLU Pro
Claude Fable 5.1
Claude Fable 5.1 leads, 92.4% against 79.2%.
Same board, both measured
Web design
Design Arena: websites
Claude Fable 5.1
Claude Fable 5.1 leads, 1312 against 967.
Same board, both measured
Long documents
Listed context window
Claude Fable 5.1
Claude Fable 5.1 takes 1M tokens against 131K.
Listed by OpenRouter
Everyday cost
1K input + 500 output tokens
gpt-oss-120b
Claude Fable 5.1 $0.035, gpt-oss-120b $0.0003 per turn.
List prices
Cost per solved task
One SWE-bench Verified task, solved
No call
Only gpt-oss-120b has the number, $0.51.
Directional only
At a glance
- Coding index
- Claude Fable 5.1 84.2 from 5 benchmarks, gpt-oss-120b not benchmarked.
- Widest category
- Agentic work, 50.8 points apart on average over 3 shared benchmarks.
- Widest single gap
- APEX-Agents: Claude Fable 5.1 68.6% against gpt-oss-120b 4.4%, 64.2 points apart on a 0 to 100 scale.
- Output price
- Claude Fable 5.1 $50.00 against gpt-oss-120b $0.50 per million output tokens, 100.0x apart.
- Context window
- Claude Fable 5.1 takes 1M tokens, gpt-oss-120b 131K.
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 Fable 5.1 | Bars | gpt-oss-120b | Ties |
|---|---|---|---|---|
| Coding | 7 | 0 | ||
| Intelligence | 2 | 0 | ||
| Agentic work | 3 | 0 | ||
| Reasoning | 7 | 0 | ||
| Math | 3 | 0 | ||
| Knowledge | 7 | 0 | ||
| Web design | 6 | 0 | ||
| General | 20 | 0 | ||
| All shared boards | 55 | 0 |
CodingLike-for-likeSix of these boards feed the Vibe Coding Index70
| Benchmark | Claude Fable 5.1 | gpt-oss-120b | Leader |
|---|---|---|---|
| Aider polyglot | Not measured | 41.8% | Only gpt-oss-120b measured |
| SWE-bench Verified | Not measured | 26.0% | Only gpt-oss-120b measured |
| LiveBench coding | 97.7% | Not measured | Only Claude Fable 5.1 measured |
| LMArena WebDev | 1743 | Not measured | Only Claude Fable 5.1 measured |
| AA Coding Index | 81.6 | 30.4 | Claude Fable 5.1 |
| LiveCodeBench (Vals AI) | 90.5% | 83.2% | Claude Fable 5.1 |
| SWE-bench Verified (Vals AI) | Not measured | 33.6% | Only gpt-oss-120b measured |
| Terminal-Bench 4 (Vals AI) | 58.1% | Not measured | Only Claude Fable 5.1 measured |
| Vibe Code Bench (Vals AI) | 90.3% | Not measured | Only Claude Fable 5.1 measured |
| Code migration (Vals AI) | 54.6% | Not measured | Only Claude Fable 5.1 measured |
| ProgramBench (Vals AI) | 7.0% | Not measured | Only Claude Fable 5.1 measured |
| IOI (Vals AI) | 90.8% | Not measured | Only Claude Fable 5.1 measured |
| Terminal-Bench 2.1 (Vals AI) | 85.0% | Not measured | Only Claude Fable 5.1 measured |
| SWE-bench Multimodal (Vals AI) | 61.3% | Not measured | Only Claude Fable 5.1 measured |
| Vibe Code Bench 1-100 (Vals AI) | 28.0% | Not measured | Only Claude Fable 5.1 measured |
| SkillsBench (Vals AI) | 61.5% | Not measured | Only Claude Fable 5.1 measured |
| CyberBench (Vals AI) | 70.4% | Not measured | Only Claude Fable 5.1 measured |
| LiveCodeBench (Artificial Analysis run) | Not measured | 87.8% | Only gpt-oss-120b measured |
| SciCode | 63.1% | 34.0% | Claude Fable 5.1 |
| Terminal-Bench Hard (Artificial Analysis run) | Not measured | 23.5% | Only gpt-oss-120b measured |
| Terminal-Bench | Not measured | 18.7% | Only gpt-oss-120b measured |
| FrontierCode | 50.9% | Not measured | Only Claude Fable 5.1 measured |
| FrontierSWE | 56.3% | Not measured | Only Claude Fable 5.1 measured |
| GSO-Bench | 88.2% | Not measured | Only Claude Fable 5.1 measured |
| WeirdML | 92.9% | 48.2% | Claude Fable 5.1 |
| MirrorCode | 73.3% | Not measured | Only Claude Fable 5.1 measured |
| ALE-Bench | 2143.2 | 575.6 | Claude Fable 5.1 |
| LMArena Text: coding | 1532 | 1379 | Claude Fable 5.1 |
| LMArena Text: software and IT | 1530 | 1387 | Claude Fable 5.1 |
| LMArena WebDev: React | 1792 | Not measured | Only Claude Fable 5.1 measured |
| LMArena WebDev: HTML | 1684 | Not measured | Only Claude Fable 5.1 measured |
| LMArena WebDev: from an image | 1722 | Not measured | Only Claude Fable 5.1 measured |
| SciCode | Not measured | 7.7% | Only gpt-oss-120b measured |
| Neither model has a result on the other 6 boards here | |||
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index20
| Benchmark | Claude Fable 5.1 | gpt-oss-120b | Leader |
|---|---|---|---|
| AA Intelligence Index | 53.4 | 11.6 | Claude Fable 5.1 |
| Epoch Capabilities Index | 166.5 | 139.8 | Claude Fable 5.1 |
Agentic workLike-for-likePublic boards, shown as published, kept out of the index30
| Benchmark | Claude Fable 5.1 | gpt-oss-120b | Leader |
|---|---|---|---|
| AA Agentic Index | 57.9 | 3.7 | Claude Fable 5.1 |
| Design Arena: agents building web apps | 1318 | Not measured | Only Claude Fable 5.1 measured |
| Design Arena: agents building full-stack apps | 1326 | Not measured | Only Claude Fable 5.1 measured |
| Design Arena: agents building mobile apps | 1267 | Not measured | Only Claude Fable 5.1 measured |
| Design Arena: agents building Godot games | 1327 | Not measured | Only Claude Fable 5.1 measured |
| Design Arena: PowerPoint slides | 1305 | Not measured | Only Claude Fable 5.1 measured |
| Design Arena: spreadsheets | 1380 | Not measured | Only Claude Fable 5.1 measured |
| LiveBench research | 82.0% | Not measured | Only Claude Fable 5.1 measured |
| LiveBench browser | 100.0% | Not measured | Only Claude Fable 5.1 measured |
| LiveBench long agentic | 80.8% | Not measured | Only Claude Fable 5.1 measured |
| SREBench (Vals AI) | 22.9% | Not measured | Only Claude Fable 5.1 measured |
| Finance Agent (Vals AI) | 58.9% | Not measured | Only Claude Fable 5.1 measured |
| Tax Agent Bench (Vals AI) | 49.2% | Not measured | Only Claude Fable 5.1 measured |
| Legal Research Bench (Vals AI) | 55.3% | Not measured | Only Claude Fable 5.1 measured |
| Excel Modeling Benchmark (Vals AI) | 76.7% | Not measured | Only Claude Fable 5.1 measured |
| Terminal-Bench-Science (Vals AI) | 40.0% | Not measured | Only Claude Fable 5.1 measured |
| Time Horizon Index (Vals AI) | 63.3% | Not measured | Only Claude Fable 5.1 measured |
| CUA-bench (Vals AI) | 13.2% | Not measured | Only Claude Fable 5.1 measured |
| Robo-bench (Vals AI) | 5.8% | Not measured | Only Claude Fable 5.1 measured |
| τ²-Bench Telecom | Not measured | 65.8% | Only gpt-oss-120b measured |
| APEX-Agents | 68.6% | 4.4% | Claude Fable 5.1 |
| METR time horizons | Not measured | 56.6% | Only gpt-oss-120b measured |
| Remote Labor Index | 17.9% | Not measured | Only Claude Fable 5.1 measured |
| SpireClimb | 2.0% | Not measured | Only Claude Fable 5.1 measured |
| Vending-Bench 2 | $5,422 | -$22 | Claude Fable 5.1 |
| LMArena Search | 1246 | Not measured | Only Claude Fable 5.1 measured |
| BrowseComp-Plus | Not measured | 67.0% | Only gpt-oss-120b measured |
| Neither model has a result on the other 14 boards here | |||
ReasoningLike-for-likePublic boards, shown as published, kept out of the index70
| Benchmark | Claude Fable 5.1 | gpt-oss-120b | Leader |
|---|---|---|---|
| GPQA Diamond | 93.4% | 78.5% | Claude Fable 5.1 |
| LiveBench reasoning | 91.7% | Not measured | Only Claude Fable 5.1 measured |
| MysteryMechanism (Vals AI) | 47.8% | Not measured | Only Claude Fable 5.1 measured |
| MMMU Pro (Vals AI) | 90.6% | Not measured | Only Claude Fable 5.1 measured |
| GPQA Diamond (Artificial Analysis run) | 93.7% | 78.2% | Claude Fable 5.1 |
| Humanity's Last Exam (Artificial Analysis run) | 59.1% | 19.6% | Claude Fable 5.1 |
| GPQA Diamond (Epoch AI run) | Not measured | 75.8% | Only gpt-oss-120b measured |
| ARC-AGI | 97.5% | Not measured | Only Claude Fable 5.1 measured |
| ARC-AGI-2 | 90.0% | Not measured | Only Claude Fable 5.1 measured |
| SimpleBench | Not measured | 22.1% | Only gpt-oss-120b measured |
| Chess puzzles | 48.0% | Not measured | Only Claude Fable 5.1 measured |
| Mystery game puzzles | 58.0% | 2.0% | Claude Fable 5.1 |
| EBR-bench | 57.1% | Not measured | Only Claude Fable 5.1 measured |
| LMArena Text: hard prompts | 1528 | 1364 | Claude Fable 5.1 |
| LMArena Text: expert | 1544 | 1356 | Claude Fable 5.1 |
| LMArena Text: hard prompts in English | 1522 | 1368 | Claude Fable 5.1 |
| LMArena Vision: diagrams | 1343 | Not measured | Only Claude Fable 5.1 measured |
| LMArena Vision: homework | 1345 | Not measured | Only Claude Fable 5.1 measured |
| Kagi LLM Benchmark | Not measured | 58.6% | Only gpt-oss-120b measured |
| Neither model has a result on the other 3 boards here | |||
MathLike-for-likePublic boards, shown as published, kept out of the index30
| Benchmark | Claude Fable 5.1 | gpt-oss-120b | Leader |
|---|---|---|---|
| AIME | Not measured | 92.6% | Only gpt-oss-120b measured |
| MATH 500 (Vals AI) | Not measured | 94.8% | Only gpt-oss-120b measured |
| MGSM (Vals AI) | Not measured | 92.0% | Only gpt-oss-120b measured |
| AA Math Index | Not measured | 93.4 | Only gpt-oss-120b measured |
| AIME 2025 (Artificial Analysis run) | Not measured | 93.4% | Only gpt-oss-120b measured |
| OTIS Mock AIME | 100.0% | 88.9% | Claude Fable 5.1 |
| FrontierMath, tiers 1 to 3 | 90.2% | Not measured | Only Claude Fable 5.1 measured |
| FrontierMath, tier 4 | 87.8% | Not measured | Only Claude Fable 5.1 measured |
| ProofBench | 100.0% | Not measured | Only Claude Fable 5.1 measured |
| LMArena Text: math | 1531 | 1389 | Claude Fable 5.1 |
| LMArena Text: mathematical work | 1541 | 1386 | Claude Fable 5.1 |
| Neither model has a result on the other 2 boards here | |||
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index70
| Benchmark | Claude Fable 5.1 | gpt-oss-120b | Leader |
|---|---|---|---|
| MMLU Pro | 92.4% | 79.2% | Claude Fable 5.1 |
| LegalBench (Vals AI) | 88.5% | 75.9% | Claude Fable 5.1 |
| CaseLaw (Vals AI) | Not measured | 48.8% | Only gpt-oss-120b measured |
| CorpFin (Vals AI) | Not measured | 58.2% | Only gpt-oss-120b measured |
| TaxEval (Vals AI) | 76.0% | 71.6% | Claude Fable 5.1 |
| MortgageTax (Vals AI) | 70.8% | Not measured | Only Claude Fable 5.1 measured |
| MedQA (Vals AI) | Not measured | 91.4% | Only gpt-oss-120b measured |
| MedCode (Vals AI) | 53.5% | Not measured | Only Claude Fable 5.1 measured |
| MMLU Pro (Artificial Analysis run) | Not measured | 80.8% | Only gpt-oss-120b measured |
| SimpleQA Verified | 70.8% | Not measured | Only Claude Fable 5.1 measured |
| LMArena Text: science | 1532 | 1382 | Claude Fable 5.1 |
| LMArena Text: medicine and healthcare | 1531 | 1388 | Claude Fable 5.1 |
| LMArena Text: legal and government | 1514 | 1355 | Claude Fable 5.1 |
| LMArena Text: business and finance | 1493 | 1359 | Claude Fable 5.1 |
| Neither model has a result on the other 4 boards here | |||
Web designLike-for-likePublic boards, shown as published, kept out of the index60
| Benchmark | Claude Fable 5.1 | gpt-oss-120b | Leader |
|---|---|---|---|
| Design Arena: websites | 1312 | 967 | Claude Fable 5.1 |
| Design Arena: UI components | 1336 | 924 | Claude Fable 5.1 |
| Design Arena: game dev | 1381 | 992 | Claude Fable 5.1 |
| Design Arena: data viz | 1344 | 987 | Claude Fable 5.1 |
| Design Arena: 3D | 1392 | 901 | Claude Fable 5.1 |
| Design Arena: all code categories | 1335 | 962 | Claude Fable 5.1 |
| Design Arena: SVG | 1300 | Not measured | Only Claude Fable 5.1 measured |
| Design Arena: ASCII art | 1323 | Not measured | Only Claude Fable 5.1 measured |
| LiveBench design | 83.4% | Not measured | Only Claude Fable 5.1 measured |
GeneralLike-for-likePublic boards, shown as published, kept out of the index200
| Benchmark | Claude Fable 5.1 | gpt-oss-120b | Leader |
|---|---|---|---|
| LiveBench data analysis | 80.3% | Not measured | Only Claude Fable 5.1 measured |
| Public Benefits Bench (Vals AI) | 74.9% | Not measured | Only Claude Fable 5.1 measured |
| SAGE (Vals AI) | 48.5% | Not measured | Only Claude Fable 5.1 measured |
| MedScribe (Vals AI) | 91.3% | Not measured | Only Claude Fable 5.1 measured |
| IFBench | Not measured | 69.0% | Only gpt-oss-120b measured |
| Long context reasoning (AA-LCR) | 85.3% | 52.0% | Claude Fable 5.1 |
| DTBench | 97.6% | 76.3% | Claude Fable 5.1 |
| LMCA | 65.5% | 22.1% | Claude Fable 5.1 |
| Fiction.LiveBench | Not measured | 44.4% | Only gpt-oss-120b measured |
| Creative writing (Lech Mazur) | Not measured | 77.1% | Only gpt-oss-120b measured |
| Surface Evolver Bench | Not measured | 25.0% | Only gpt-oss-120b measured |
| Furniture assembly | 70.0% | Not measured | Only Claude Fable 5.1 measured |
| LMArena Text | 1512 | 1366 | Claude Fable 5.1 |
| LMArena Text: instruction following | 1518 | 1318 | Claude Fable 5.1 |
| LMArena Text: creative writing | 1509 | 1274 | Claude Fable 5.1 |
| LMArena Vision | 1319 | Not measured | Only Claude Fable 5.1 measured |
| LMArena Text: English | 1506 | 1375 | Claude Fable 5.1 |
| LMArena Text: non-English | 1508 | 1351 | Claude Fable 5.1 |
| LMArena Text: Chinese | 1584 | 1385 | Claude Fable 5.1 |
| LMArena Text: German | 1499 | 1353 | Claude Fable 5.1 |
| LMArena Text: Japanese | 1562 | 1331 | Claude Fable 5.1 |
| LMArena Text: Korean | 1517 | 1282 | Claude Fable 5.1 |
| LMArena Text: French | 1523 | 1370 | Claude Fable 5.1 |
| LMArena Text: Spanish | 1520 | 1389 | Claude Fable 5.1 |
| LMArena Text: Russian | 1520 | 1343 | Claude Fable 5.1 |
| LMArena Text: Polish | 1525 | 1353 | Claude Fable 5.1 |
| LMArena Text: multi-turn | 1493 | 1340 | Claude Fable 5.1 |
| LMArena Text: longer queries | 1524 | 1319 | Claude Fable 5.1 |
| LMArena Text: writing and language | 1510 | 1306 | Claude Fable 5.1 |
| LMArena Text: entertainment and media | 1497 | 1292 | Claude Fable 5.1 |
| LMArena Vision: English | 1313 | Not measured | Only Claude Fable 5.1 measured |
| LMArena Vision: Chinese | 1391 | Not measured | Only Claude Fable 5.1 measured |
| LMArena Vision: reading text | 1327 | Not measured | Only Claude Fable 5.1 measured |
| LMArena Vision: humor | 1318 | Not measured | Only Claude Fable 5.1 measured |
| LMArena Vision: creative writing | 1330 | Not measured | Only Claude Fable 5.1 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 Fable 5.1 | gpt-oss-120b | 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 Fable 5.1$0.035Fits in one request
gpt-oss-120b$0.0003Fits in one request
gpt-oss-120b costs less
Repository review
50K input + 3K output tokens
Claude Fable 5.1$0.650Fits in one request
gpt-oss-120b$0.0065Fits in one request
gpt-oss-120b costs less
Agent loop
200K input + 10K output tokens
Claude Fable 5.1$2.50Fits in one request
gpt-oss-120b$0.025Exceeds the context window
gpt-oss-120b 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 Fable 5.1 | OpenAI gpt-oss-120b |
|---|---|---|
| Maker | Anthropic | OpenAI |
| Weights | No public weights listed | Open weights |
| Released | September 1, 2026 | August 5, 2025 |
| Context window | 1M | 131K |
| Input $/Mtok | $10.00 | $0.10 |
| Output $/Mtok | $50.00 | $0.50 |
| Coding index | 84.2 | Not benchmarked |
| Independent measurements behind it | 5 | 1 |
| Cost per solved task | Not computable | $0.51 |
| Source | OpenRouter listing | OpenRouter listing |
Questions
Is Claude Fable 5.1 better than gpt-oss-120b for coding?
Only Claude Fable 5.1 has a coding score, 84.2 on the Vibe Coding Index; gpt-oss-120b has none, so the two cannot be ranked on coding. Pick gpt-oss-120b for output tokens 100.0x cheaper ($0.50 vs $50.00 per million).
Which is cheaper, Claude Fable 5.1 or gpt-oss-120b?
Claude Fable 5.1 costs $10.00 per million input tokens and $50.00 per million output tokens; gpt-oss-120b costs $0.10 and $0.50. Cost per solved task is known for gpt-oss-120b only.
Which has the bigger context window, Claude Fable 5.1 or gpt-oss-120b?
Claude Fable 5.1, with 1M tokens against 131K.
How many benchmarks is the Claude Fable 5.1 vs gpt-oss-120b comparison based on?
55 benchmarks have a result for both models as of October 22, 2026. Claude Fable 5.1's coding index rests on 5 independent benchmarks and gpt-oss-120b's on 1. Where only one model has a result, the page says so instead of naming a winner.