Claude Fable 5.1 vs GPT-6.1 Terra
Claude Fable 5.1 leads GPT-6.1 Terra on coding, 84.3 to 77.4 on the Vibe Coding Index, and GPT-6.1 Terra costs 10.0x less per output token ($5.00 vs $50.00 per million). Updated October 29, 2026; 32 benchmarks have a result for both.
vs boards won of 32 shared, 1 tied
Claude Fable 5.1 or GPT-6.1 Terra: which to pick
Pick Claude Fable 5.1 for coding: it scores 84.3 on the Vibe Coding Index against 77.4 for GPT-6.1 Terra.
Pick GPT-6.1 Terra for output tokens 10.0x cheaper ($5.00 vs $50.00 per million) and a larger context window (1.05M against 1M tokens).
Model AClaude Fable 5.1Anthropic84.3/1005 independent benchmarksNo cost per solved taskModel BGPT-6.1 TerraOpenAI77.4/1004 independent benchmarksNo cost per solved task
- Shared results
- 32
- Claude Fable 5.1 only
- 101
- GPT-6.1 Terra only
- 4
- 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
Claude Fable 5.1
Claude Fable 5.1 scores 84.3 against 77.4.
5 and 4 benchmarks behind the scores
Intelligence
AA Intelligence Index
GPT-6.1 Terra
GPT-6.1 Terra leads, 51.0 against 49.7.
Same board, both measured
Agentic work
AA Agentic Index
No call
Only Claude Fable 5.1 has a AA Agentic Index result, 57.2.
Directional only
Reasoning
GPQA Diamond
No call
Only Claude Fable 5.1 has a GPQA Diamond result, 93.4%.
Directional only
Knowledge
MMLU Pro
No call
Only Claude Fable 5.1 has a MMLU Pro result, 92.4%.
Directional only
Web design
Design Arena: websites
Claude Fable 5.1
Claude Fable 5.1 leads, 1312 against 1283.
Same board, both measured
General
Vals Index
No call
Only GPT-6.1 Terra has a Vals Index result, 60.5%.
Directional only
Long documents
Listed context window
GPT-6.1 Terra
GPT-6.1 Terra takes 1.05M tokens against 1M.
Listed by OpenRouter
Everyday cost
1K input + 500 output tokens
GPT-6.1 Terra
Claude Fable 5.1 $0.035, GPT-6.1 Terra $0.0035 per turn.
List prices
At a glance
- Coding index
- Claude Fable 5.1 84.3 from 5 benchmarks, GPT-6.1 Terra 77.4 from 4 benchmarks.
- Widest category
- Agentic work, 17.4 points apart on average over 6 shared benchmarks.
- Widest single gap
- Tax Agent Bench (Vals AI): Claude Fable 5.1 49.2% against GPT-6.1 Terra 15.2%, 34.0 points apart on a 0 to 100 scale.
- Output price
- Claude Fable 5.1 $50.00 against GPT-6.1 Terra $5.00 per million output tokens, 10.0x apart.
- Context window
- Claude Fable 5.1 takes 1M tokens, GPT-6.1 Terra 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 Fable 5.1 | Bars | GPT-6.1 Terra | Ties |
|---|---|---|---|---|
| Coding | 6 | 2 | ||
| Intelligence | 0 | 1 | ||
| Agentic work | 5 | 1 | ||
| Reasoning | 3 | 2 | ||
| Math | 0 | 2 | 1 tie | |
| Knowledge | 1 | 0 | ||
| Web design | 5 | 0 | ||
| General | 1 | 2 | ||
| All shared boards | 21 | 10 | 1 tie |
CodingLike-for-likeSix of these boards feed the Vibe Coding Index62
| Benchmark | Claude Fable 5.1 | GPT-6.1 Terra | Leader |
|---|---|---|---|
| LiveBench coding | 97.7% | 94.3% | Claude Fable 5.1 |
| LMArena WebDev | 1746 | 1673 | Claude Fable 5.1 |
| AA Coding Index | 80.7 | Not measured | Only Claude Fable 5.1 measured |
| LiveCodeBench (Vals AI) | 90.5% | Not measured | Only Claude Fable 5.1 measured |
| Terminal-Bench 4 (Vals AI) | 58.1% | 49.5% | Claude Fable 5.1 |
| Vibe Code Bench (Vals AI) | 90.3% | 84.0% | Claude Fable 5.1 |
| 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 |
| SciCode | 63.1% | 55.1% | Claude Fable 5.1 |
| 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% | Not measured | Only Claude Fable 5.1 measured |
| MirrorCode | 73.3% | Not measured | Only Claude Fable 5.1 measured |
| ALE-Bench | 2143.2 | 2608.8 | GPT-6.1 Terra |
| LMArena Text: coding | 1530 | Not measured | Only Claude Fable 5.1 measured |
| LMArena Text: software and IT | 1529 | Not measured | Only Claude Fable 5.1 measured |
| LMArena WebDev: React | 1792 | 1657 | Claude Fable 5.1 |
| LMArena WebDev: HTML | 1683 | 1719 | GPT-6.1 Terra |
| LMArena WebDev: from an image | 1722 | Not measured | Only Claude Fable 5.1 measured |
| SWE-Bench Pro V2 | 99.1% | Not measured | Only Claude Fable 5.1 measured |
| SWE Atlas: Codebase QnA | 60.0% | Not measured | Only Claude Fable 5.1 measured |
| SWE Atlas: Refactoring | 56.7% | Not measured | Only Claude Fable 5.1 measured |
| SWE Atlas: Test Writing | 67.0% | Not measured | Only Claude Fable 5.1 measured |
| Neither model has a result on the other 13 boards here | |||
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index01
| Benchmark | Claude Fable 5.1 | GPT-6.1 Terra | Leader |
|---|---|---|---|
| AA Intelligence Index | 49.7 | 51.0 | GPT-6.1 Terra |
| Epoch Capabilities Index | 166.5 | Not measured | Only Claude Fable 5.1 measured |
Agentic workLike-for-likePublic boards, shown as published, kept out of the index51
| Benchmark | Claude Fable 5.1 | GPT-6.1 Terra | Leader |
|---|---|---|---|
| AA Agentic Index | 57.2 | Not measured | Only Claude Fable 5.1 measured |
| 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 | 1264 | 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: HTML slides | 1394 | Not measured | Only Claude Fable 5.1 measured |
| Design Arena: PowerPoint slides | 1318 | Not measured | Only Claude Fable 5.1 measured |
| Design Arena: spreadsheets | 1417 | Not measured | Only Claude Fable 5.1 measured |
| LiveBench research | 82.0% | 73.9% | Claude Fable 5.1 |
| LiveBench browser | 89.8% | 93.1% | GPT-6.1 Terra |
| LiveBench long agentic | 77.9% | 48.6% | Claude Fable 5.1 |
| 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% | 15.2% | Claude Fable 5.1 |
| Legal Research Bench (Vals AI) | 55.3% | 26.0% | Claude Fable 5.1 |
| Harvey's Legal Agent Benchmark (Vals AI) | Not measured | 1.7% | Only GPT-6.1 Terra 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 |
| APEX-Agents | 68.6% | 68.3% | Claude Fable 5.1 |
| 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 | Not measured | Only Claude Fable 5.1 measured |
| LMArena Search | 1246 | Not measured | Only Claude Fable 5.1 measured |
| MCP Atlas | 87.2% | Not measured | Only Claude Fable 5.1 measured |
| Neither model has a result on the other 15 boards here | |||
ReasoningLike-for-likePublic boards, shown as published, kept out of the index32
| Benchmark | Claude Fable 5.1 | GPT-6.1 Terra | Leader |
|---|---|---|---|
| GPQA Diamond | 93.4% | Not measured | Only Claude Fable 5.1 measured |
| LiveBench reasoning | 91.7% | 88.7% | Claude Fable 5.1 |
| 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% | Not measured | Only Claude Fable 5.1 measured |
| Humanity's Last Exam (Artificial Analysis run) | 59.1% | 46.2% | Claude Fable 5.1 |
| GPQA Diamond (Epoch AI run) | Not measured | 94.3% | Only GPT-6.1 Terra 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 |
| Chess puzzles | 48.0% | Not measured | Only Claude Fable 5.1 measured |
| Mystery game puzzles | 58.0% | 74.0% | GPT-6.1 Terra |
| EBR-bench | 57.1% | 78.1% | GPT-6.1 Terra |
| LMArena Text: hard prompts | 1529 | Not measured | Only Claude Fable 5.1 measured |
| LMArena Text: expert | 1545 | Not measured | Only Claude Fable 5.1 measured |
| LMArena Text: hard prompts in English | 1523 | Not measured | Only Claude Fable 5.1 measured |
| LMArena Vision: diagrams | 1343 | Not measured | Only Claude Fable 5.1 measured |
| LMArena Vision: homework | 1345 | Not measured | Only Claude Fable 5.1 measured |
| Humanity's Last Exam (Scale run) | 51.3% | 35.7% | Claude Fable 5.1 |
| Neither model has a result on the other 5 boards here | |||
MathLike-for-likePublic boards, shown as published, kept out of the index02
| Benchmark | Claude Fable 5.1 | GPT-6.1 Terra | Leader |
|---|---|---|---|
| OTIS Mock AIME | 100.0% | 100.0% | Tie |
| FrontierMath, tiers 1 to 3 | 90.2% | 90.9% | GPT-6.1 Terra |
| FrontierMath, tier 4 | 87.8% | 92.7% | GPT-6.1 Terra |
| ProofBench | 100.0% | Not measured | Only Claude Fable 5.1 measured |
| LMArena Text: math | 1531 | Not measured | Only Claude Fable 5.1 measured |
| LMArena Text: mathematical work | 1544 | Not measured | Only Claude Fable 5.1 measured |
| MathArena | 77.9% | Not measured | Only Claude Fable 5.1 measured |
| Neither model has a result on the other 7 boards here | |||
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index10
| Benchmark | Claude Fable 5.1 | GPT-6.1 Terra | Leader |
|---|---|---|---|
| MMLU Pro | 92.4% | Not measured | Only Claude Fable 5.1 measured |
| LegalBench (Vals AI) | 88.5% | Not measured | Only Claude Fable 5.1 measured |
| TaxEval (Vals AI) | 76.0% | Not measured | Only Claude Fable 5.1 measured |
| MortgageTax (Vals AI) | 70.8% | Not measured | Only Claude Fable 5.1 measured |
| MedCode (Vals AI) | 53.5% | Not measured | Only Claude Fable 5.1 measured |
| SimpleQA Verified | 70.8% | 57.3% | Claude Fable 5.1 |
| LMArena Text: science | 1535 | Not measured | Only Claude Fable 5.1 measured |
| LMArena Text: medicine and healthcare | 1535 | Not measured | Only Claude Fable 5.1 measured |
| LMArena Text: legal and government | 1513 | Not measured | Only Claude Fable 5.1 measured |
| LMArena Text: business and finance | 1494 | Not measured | Only Claude Fable 5.1 measured |
| PRBench Finance | 50.8% | Not measured | Only Claude Fable 5.1 measured |
| PRBench Legal | 51.6% | Not measured | Only Claude Fable 5.1 measured |
| Neither model has a result on the other 8 boards here | |||
Web designLike-for-likePublic boards, shown as published, kept out of the index50
| Benchmark | Claude Fable 5.1 | GPT-6.1 Terra | Leader |
|---|---|---|---|
| Design Arena: websites | 1312 | 1283 | Claude Fable 5.1 |
| Design Arena: UI components | 1333 | 1277 | Claude Fable 5.1 |
| Design Arena: game dev | 1381 | 1348 | Claude Fable 5.1 |
| Design Arena: data viz | 1345 | Not measured | Only Claude Fable 5.1 measured |
| Design Arena: 3D | 1390 | Not measured | Only Claude Fable 5.1 measured |
| Design Arena: all code categories | 1334 | 1295 | Claude Fable 5.1 |
| Design Arena: SVG | 1297 | Not measured | Only Claude Fable 5.1 measured |
| Design Arena: ASCII art | 1322 | Not measured | Only Claude Fable 5.1 measured |
| LiveBench design | 83.4% | 82.3% | Claude Fable 5.1 |
GeneralLike-for-likePublic boards, shown as published, kept out of the index12
| Benchmark | Claude Fable 5.1 | GPT-6.1 Terra | Leader |
|---|---|---|---|
| Vals Index | Not measured | 60.5% | Only GPT-6.1 Terra measured |
| LiveBench data analysis | 80.3% | 82.3% | GPT-6.1 Terra |
| Public Benefits Bench (Vals AI) | 74.9% | Not measured | Only Claude Fable 5.1 measured |
| MedScribe (Vals AI) | 91.3% | Not measured | Only Claude Fable 5.1 measured |
| Long context reasoning (AA-LCR) | 85.3% | 82.7% | Claude Fable 5.1 |
| DTBench | 97.6% | Not measured | Only Claude Fable 5.1 measured |
| LMCA | 65.5% | Not measured | Only Claude Fable 5.1 measured |
| Furniture assembly | 70.0% | 79.2% | GPT-6.1 Terra |
| LMArena Text | 1514 | Not measured | Only Claude Fable 5.1 measured |
| LMArena Text: instruction following | 1519 | Not measured | Only Claude Fable 5.1 measured |
| LMArena Text: creative writing | 1512 | Not measured | Only Claude Fable 5.1 measured |
| LMArena Vision | 1319 | Not measured | Only Claude Fable 5.1 measured |
| LMArena Text: English | 1508 | Not measured | Only Claude Fable 5.1 measured |
| LMArena Text: non-English | 1510 | Not measured | Only Claude Fable 5.1 measured |
| LMArena Text: Chinese | 1581 | Not measured | Only Claude Fable 5.1 measured |
| LMArena Text: German | 1496 | Not measured | Only Claude Fable 5.1 measured |
| LMArena Text: Japanese | 1562 | Not measured | Only Claude Fable 5.1 measured |
| LMArena Text: Korean | 1514 | Not measured | Only Claude Fable 5.1 measured |
| LMArena Text: French | 1521 | Not measured | Only Claude Fable 5.1 measured |
| LMArena Text: Spanish | 1518 | Not measured | Only Claude Fable 5.1 measured |
| LMArena Text: Russian | 1521 | Not measured | Only Claude Fable 5.1 measured |
| LMArena Text: Polish | 1536 | Not measured | Only Claude Fable 5.1 measured |
| LMArena Text: multi-turn | 1495 | Not measured | Only Claude Fable 5.1 measured |
| LMArena Text: longer queries | 1525 | Not measured | Only Claude Fable 5.1 measured |
| LMArena Text: writing and language | 1514 | Not measured | Only Claude Fable 5.1 measured |
| LMArena Text: entertainment and media | 1499 | Not measured | Only Claude Fable 5.1 measured |
| 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 |
| MultiChallenge | Not measured | 74.2% | Only GPT-6.1 Terra measured |
| Neither model has a result on the other 16 boards here | |||
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
| Benchmark | Claude Fable 5.1 | GPT-6.1 Terra | 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-6.1 Terra$0.0035Fits in one request
GPT-6.1 Terra costs less
Repository review
50K input + 3K output tokens
Claude Fable 5.1$0.650Fits in one request
GPT-6.1 Terra$0.065Fits in one request
GPT-6.1 Terra costs less
Agent loop
200K input + 10K output tokens
Claude Fable 5.1$2.50Fits in one request
GPT-6.1 Terra$0.250Fits in one request
GPT-6.1 Terra 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-6.1 Terra |
|---|---|---|
| Maker | Anthropic | OpenAI |
| Weights | No public weights listed | No public weights listed |
| Released | September 1, 2026 | October 26, 2026 |
| Context window | 1M | 1.05M |
| Input $/Mtok | $10.00 | $1.00 |
| Output $/Mtok | $50.00 | $5.00 |
| Coding index | 84.3 | 77.4 |
| Independent measurements behind it | 5 | 4 |
| Cost per solved task | Not computable | Not computable |
| Source | OpenRouter listing | OpenRouter listing |
Questions
Is Claude Fable 5.1 better than GPT-6.1 Terra for coding?
Pick Claude Fable 5.1 for coding: it scores 84.3 on the Vibe Coding Index against 77.4 for GPT-6.1 Terra. Pick GPT-6.1 Terra for output tokens 10.0x cheaper ($5.00 vs $50.00 per million) and a larger context window (1.05M against 1M tokens).
Which is cheaper, Claude Fable 5.1 or GPT-6.1 Terra?
Claude Fable 5.1 costs $10.00 per million input tokens and $50.00 per million output tokens; GPT-6.1 Terra costs $1.00 and $5.00. Cost per solved task is known for neither of them.
Which has the bigger context window, Claude Fable 5.1 or GPT-6.1 Terra?
GPT-6.1 Terra, with 1.05M tokens against 1M.
How many benchmarks is the Claude Fable 5.1 vs GPT-6.1 Terra comparison based on?
32 benchmarks have a result for both models as of October 29, 2026. Claude Fable 5.1's coding index rests on 5 independent benchmarks and GPT-6.1 Terra's on 4. Where only one model has a result, the page says so instead of naming a winner.