Claude Fable 5.1 vs Gemini 3 Flash Preview
Updated October 21, 2026. 46 benchmarks have a result for both. Coding is ranked on the Vibe Coding Index; every other board is shown as published.
vs boards won of 46 shared
Decision reading
Pick Claude Fable 5.1 for coding: it scores 89.1 on the Vibe Coding Index against 75.8 for Gemini 3 Flash Preview.
Pick Gemini 3 Flash Preview when output tokens cost 16.7x less, or when the context window is larger, 1.05M against 1M tokens.
Model AClaude Fable 5.1Anthropic89.1/1002 independent benchmarksNo cost per solved taskModel BGemini 3 Flash PreviewGoogle75.8/1001 independent benchmark$0.37 per solved task
- Shared results
- 46
- Claude Fable 5.1 only
- 78
- Gemini 3 Flash Preview only
- 23
- Like-for-like categories
- 8 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
Claude Fable 5.1
Claude Fable 5.1 scores 89.1 against 75.8.
2 and 1 benchmarks behind the scores
Intelligence
AA Intelligence Index
Claude Fable 5.1
Claude Fable 5.1 leads, 53.4 against 26.3.
Same board, both measured
Agentic work
AA Agentic Index
No call
Only Claude Fable 5.1 has a AA Agentic Index result, 57.9.
Directional only
Reasoning
GPQA Diamond
Claude Fable 5.1
Claude Fable 5.1 leads, 93.4% against 87.9%.
Same board, both measured
Math
AIME
No call
Only Gemini 3 Flash Preview has a AIME result, 95.6%.
Directional only
Knowledge
MMLU Pro
Claude Fable 5.1
Claude Fable 5.1 leads, 92.4% against 88.6%.
Same board, both measured
Web design
Design Arena: websites
Claude Fable 5.1
Claude Fable 5.1 leads, 1313 against 1196.
Same board, both measured
Long documents
Listed context window
Gemini 3 Flash Preview
Gemini 3 Flash Preview takes 1.05M tokens against 1M.
Listed by OpenRouter
Everyday cost
1K input + 500 output tokens
Gemini 3 Flash Preview
Claude Fable 5.1 $0.035, Gemini 3 Flash Preview $0.0020 per turn.
List prices
Cost per solved task
One SWE-bench Verified task, solved
No call
Only Gemini 3 Flash Preview has the number, $0.37.
Directional only
At a glance
- Coding index
- Claude Fable 5.1 89.1 from 2 benchmarks, Gemini 3 Flash Preview 75.8 from 1 benchmark.
- Widest category
- Math, 49.8 points apart on average over 4 shared benchmarks.
- Widest single gap
- ProofBench: Claude Fable 5.1 100.0% against Gemini 3 Flash Preview 15.0%, 85.0 points apart on a 0 to 100 scale.
- Output price
- Claude Fable 5.1 $50.00 against Gemini 3 Flash Preview $3.00 per million output tokens, 16.7x apart.
- Context window
- Claude Fable 5.1 takes 1M tokens, Gemini 3 Flash Preview 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 | Gemini 3 Flash Preview | Ties |
|---|---|---|---|---|
| Coding | 8 | 0 | ||
| Intelligence | 1 | 0 | ||
| Agentic work | 10 | 0 | ||
| Reasoning | 8 | 0 | ||
| Math | 4 | 0 | ||
| Knowledge | 5 | 1 | ||
| Web design | 4 | 0 | ||
| General | 4 | 1 | ||
| All shared boards | 44 | 2 |
CodingLike-for-likeFour of these boards feed the Vibe Coding Index80
| Benchmark | Claude Fable 5.1 | Gemini 3 Flash Preview | Leader |
|---|---|---|---|
| SWE-bench Verified | Not measured | 75.8% | Only Gemini 3 Flash Preview 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 | Not measured | Only Claude Fable 5.1 measured |
| LiveCodeBench (Vals AI) | 90.5% | 85.6% | Claude Fable 5.1 |
| SWE-bench Verified (Vals AI) | Not measured | 75.0% | Only Gemini 3 Flash Preview measured |
| Terminal-Bench 4 (Vals AI) | 58.1% | Not measured | Only Claude Fable 5.1 measured |
| Vibe Code Bench (Vals AI) | 90.3% | 20.2% | Claude Fable 5.1 |
| Code migration (Vals AI) | 54.6% | 6.4% | Claude Fable 5.1 |
| ProgramBench (Vals AI) | 7.0% | 0.0% | Claude Fable 5.1 |
| IOI (Vals AI) | 90.8% | Not measured | Only Claude Fable 5.1 measured |
| Terminal-Bench 2.1 (Vals AI) | 85.0% | 53.9% | Claude Fable 5.1 |
| 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 | 90.8% | Only Gemini 3 Flash Preview measured |
| SciCode | 63.1% | Not measured | Only Claude Fable 5.1 measured |
| Terminal-Bench Hard (Artificial Analysis run) | Not measured | 38.6% | Only Gemini 3 Flash Preview measured |
| Terminal-Bench | Not measured | 64.3% | Only Gemini 3 Flash Preview 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% | 9.8% | Claude Fable 5.1 |
| WeirdML | 92.9% | 61.6% | Claude Fable 5.1 |
| MirrorCode | 73.3% | Not measured | Only Claude Fable 5.1 measured |
| ALE-Bench | 2143.2 | 1367.2 | Claude Fable 5.1 |
| LMArena Text: coding | 1532 | Not measured | Only Claude Fable 5.1 measured |
| LMArena Text: software and IT | 1530 | Not measured | Only Claude Fable 5.1 measured |
| 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 |
| Neither model has a result on the other 7 boards here | |||
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index10
| Benchmark | Claude Fable 5.1 | Gemini 3 Flash Preview | Leader |
|---|---|---|---|
| AA Intelligence Index | 53.4 | 26.3 | Claude Fable 5.1 |
| 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 index100
| Benchmark | Claude Fable 5.1 | Gemini 3 Flash Preview | Leader |
|---|---|---|---|
| AA Agentic Index | 57.9 | Not measured | Only Claude Fable 5.1 measured |
| Design Arena: agents building web apps | 1318 | 1111 | Claude Fable 5.1 |
| Design Arena: agents building full-stack apps | 1326 | 1063 | Claude Fable 5.1 |
| Design Arena: agents building mobile apps | 1267 | 1090 | Claude Fable 5.1 |
| Design Arena: agents building Android apps | Not measured | 1056 | Only Gemini 3 Flash Preview measured |
| Design Arena: agents building Godot games | 1327 | 1161 | Claude Fable 5.1 |
| Design Arena: PowerPoint slides | 1328 | 1036 | Claude Fable 5.1 |
| Design Arena: spreadsheets | 1374 | 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% | 42.5% | Claude Fable 5.1 |
| Tax Agent Bench (Vals AI) | 49.2% | 11.8% | Claude Fable 5.1 |
| Legal Research Bench (Vals AI) | 55.3% | 18.3% | Claude Fable 5.1 |
| Excel Modeling Benchmark (Vals AI) | 76.7% | 26.0% | Claude Fable 5.1 |
| 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 | 80.4% | Only Gemini 3 Flash Preview measured |
| APEX-Agents | 68.6% | Not measured | Only Claude Fable 5.1 measured |
| Remote Labor Index | 17.9% | Not measured | Only Claude Fable 5.1 measured |
| BALROG | Not measured | 48.1% | Only Gemini 3 Flash Preview measured |
| DeepResearch Bench | Not measured | 49.8% | Only Gemini 3 Flash Preview measured |
| SpireClimb | 2.0% | Not measured | Only Claude Fable 5.1 measured |
| Vending-Bench 2 | $5,422 | $3,635 | Claude Fable 5.1 |
| LMArena Search | 1246 | Not measured | Only Claude Fable 5.1 measured |
| Neither model has a result on the other 11 boards here | |||
ReasoningLike-for-likePublic boards, shown as published, kept out of the index80
| Benchmark | Claude Fable 5.1 | Gemini 3 Flash Preview | Leader |
|---|---|---|---|
| GPQA Diamond | 93.4% | 87.9% | 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% | 87.6% | Claude Fable 5.1 |
| GPQA Diamond (Artificial Analysis run) | 93.7% | 89.8% | Claude Fable 5.1 |
| Humanity's Last Exam (Artificial Analysis run) | 59.1% | 36.6% | Claude Fable 5.1 |
| GPQA Diamond (Epoch AI run) | Not measured | 89.4% | Only Gemini 3 Flash Preview measured |
| ARC-AGI | 97.5% | 84.7% | Claude Fable 5.1 |
| ARC-AGI-2 | 90.0% | 33.6% | Claude Fable 5.1 |
| SimpleBench | Not measured | 61.1% | Only Gemini 3 Flash Preview measured |
| Chess puzzles | 48.0% | 39.0% | Claude Fable 5.1 |
| Mystery game puzzles | 58.0% | 26.0% | Claude Fable 5.1 |
| EBR-bench | 57.1% | Not measured | Only Claude Fable 5.1 measured |
| VPCT | Not measured | 72.6% | Only Gemini 3 Flash Preview measured |
| LMArena Text: hard prompts | 1528 | Not measured | Only Claude Fable 5.1 measured |
| LMArena Text: expert | 1544 | Not measured | Only Claude Fable 5.1 measured |
| LMArena Text: hard prompts in English | 1522 | 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 |
| Neither model has a result on the other 2 boards here | |||
MathLike-for-likePublic boards, shown as published, kept out of the index40
| Benchmark | Claude Fable 5.1 | Gemini 3 Flash Preview | Leader |
|---|---|---|---|
| AIME | Not measured | 95.6% | Only Gemini 3 Flash Preview measured |
| MGSM (Vals AI) | Not measured | 93.3% | Only Gemini 3 Flash Preview measured |
| AA Math Index | Not measured | 97.0 | Only Gemini 3 Flash Preview measured |
| AIME 2025 (Artificial Analysis run) | Not measured | 97.0% | Only Gemini 3 Flash Preview measured |
| OTIS Mock AIME | 100.0% | 95.6% | Claude Fable 5.1 |
| FrontierMath, tiers 1 to 3 | 90.2% | 51.2% | Claude Fable 5.1 |
| FrontierMath, tier 4 | 87.8% | 17.1% | Claude Fable 5.1 |
| ProofBench | 100.0% | 15.0% | Claude Fable 5.1 |
| LMArena Text: math | 1531 | Not measured | Only Claude Fable 5.1 measured |
| LMArena Text: mathematical work | 1541 | Not measured | Only Claude Fable 5.1 measured |
| Neither model has a result on the other 3 boards here | |||
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index51
| Benchmark | Claude Fable 5.1 | Gemini 3 Flash Preview | Leader |
|---|---|---|---|
| MMLU Pro | 92.4% | 88.6% | Claude Fable 5.1 |
| LegalBench (Vals AI) | 88.5% | 86.9% | Claude Fable 5.1 |
| CaseLaw (Vals AI) | Not measured | 55.8% | Only Gemini 3 Flash Preview measured |
| CorpFin (Vals AI) | Not measured | 66.4% | Only Gemini 3 Flash Preview measured |
| TaxEval (Vals AI) | 76.0% | 73.9% | Claude Fable 5.1 |
| MortgageTax (Vals AI) | 70.8% | 68.7% | Claude Fable 5.1 |
| MedQA (Vals AI) | Not measured | 95.8% | Only Gemini 3 Flash Preview measured |
| MedCode (Vals AI) | 53.5% | 55.9% | Gemini 3 Flash Preview |
| MMLU Pro (Artificial Analysis run) | Not measured | 89.0% | Only Gemini 3 Flash Preview measured |
| SimpleQA Verified | 70.8% | 66.8% | Claude Fable 5.1 |
| GeoBench | Not measured | 88.0% | Only Gemini 3 Flash Preview measured |
| LMArena Text: science | 1532 | Not measured | Only Claude Fable 5.1 measured |
| LMArena Text: medicine and healthcare | 1531 | Not measured | Only Claude Fable 5.1 measured |
| LMArena Text: legal and government | 1514 | Not measured | Only Claude Fable 5.1 measured |
| LMArena Text: business and finance | 1493 | Not measured | Only Claude Fable 5.1 measured |
| Neither model has a result on the other 2 boards here | |||
Web designLike-for-likePublic boards, shown as published, kept out of the index40
| Benchmark | Claude Fable 5.1 | Gemini 3 Flash Preview | Leader |
|---|---|---|---|
| Design Arena: websites | 1313 | 1196 | Claude Fable 5.1 |
| Design Arena: UI components | 1338 | Not measured | Only Claude Fable 5.1 measured |
| Design Arena: game dev | 1382 | 1166 | Claude Fable 5.1 |
| Design Arena: data viz | 1344 | Not measured | Only Claude Fable 5.1 measured |
| Design Arena: 3D | 1393 | 1184 | Claude Fable 5.1 |
| Design Arena: all code categories | 1336 | 1189 | Claude Fable 5.1 |
| Design Arena: SVG | 1301 | Not measured | Only Claude Fable 5.1 measured |
| Design Arena: ASCII art | 1324 | 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 index41
| Benchmark | Claude Fable 5.1 | Gemini 3 Flash Preview | 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% | 51.8% | Gemini 3 Flash Preview |
| MedScribe (Vals AI) | 91.3% | 69.9% | Claude Fable 5.1 |
| Vals Multimodal Index | Not measured | 52.2% | Only Gemini 3 Flash Preview measured |
| IFBench | Not measured | 78.0% | Only Gemini 3 Flash Preview measured |
| Long context reasoning (AA-LCR) | 85.3% | 78.0% | Claude Fable 5.1 |
| DTBench | 97.6% | 89.1% | Claude Fable 5.1 |
| LMCA | 65.5% | 43.1% | Claude Fable 5.1 |
| Furniture assembly | 70.0% | Not measured | Only Claude Fable 5.1 measured |
| LMArena Text | 1512 | Not measured | Only Claude Fable 5.1 measured |
| LMArena Text: instruction following | 1518 | Not measured | Only Claude Fable 5.1 measured |
| LMArena Text: creative writing | 1509 | Not measured | Only Claude Fable 5.1 measured |
| LMArena Vision | 1319 | Not measured | Only Claude Fable 5.1 measured |
| LMArena Text: English | 1506 | Not measured | Only Claude Fable 5.1 measured |
| LMArena Text: non-English | 1508 | Not measured | Only Claude Fable 5.1 measured |
| LMArena Text: Chinese | 1584 | Not measured | Only Claude Fable 5.1 measured |
| LMArena Text: German | 1499 | Not measured | Only Claude Fable 5.1 measured |
| LMArena Text: Japanese | 1562 | Not measured | Only Claude Fable 5.1 measured |
| LMArena Text: Korean | 1517 | Not measured | Only Claude Fable 5.1 measured |
| LMArena Text: French | 1523 | Not measured | Only Claude Fable 5.1 measured |
| LMArena Text: Spanish | 1520 | Not measured | Only Claude Fable 5.1 measured |
| LMArena Text: Russian | 1520 | Not measured | Only Claude Fable 5.1 measured |
| LMArena Text: Polish | 1525 | Not measured | Only Claude Fable 5.1 measured |
| LMArena Text: multi-turn | 1493 | Not measured | Only Claude Fable 5.1 measured |
| LMArena Text: longer queries | 1524 | Not measured | Only Claude Fable 5.1 measured |
| LMArena Text: writing and language | 1510 | Not measured | Only Claude Fable 5.1 measured |
| LMArena Text: entertainment and media | 1497 | 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 |
| 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 | Claude Fable 5.1 | Gemini 3 Flash Preview | 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
Gemini 3 Flash Preview$0.0020Fits in one request
Gemini 3 Flash Preview costs less
Repository review
50K input + 3K output tokens
Claude Fable 5.1$0.650Fits in one request
Gemini 3 Flash Preview$0.034Fits in one request
Gemini 3 Flash Preview costs less
Agent loop
200K input + 10K output tokens
Claude Fable 5.1$2.50Fits in one request
Gemini 3 Flash Preview$0.130Fits in one request
Gemini 3 Flash Preview 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 | Google Gemini 3 Flash Preview |
|---|---|---|
| Maker | Anthropic | |
| Weights | No public weights listed | No public weights listed |
| Released | September 1, 2026 | December 17, 2025 |
| Context window | 1M | 1.05M |
| Input $/Mtok | $10.00 | $0.50 |
| Output $/Mtok | $50.00 | $3.00 |
| Coding index | 89.1 | 75.8 |
| Independent measurements behind it | 2 | 1 |
| Cost per solved task | Not computable | $0.37 |
| Source | OpenRouter listing | OpenRouter listing |
Questions
Is Claude Fable 5.1 better than Gemini 3 Flash Preview for coding?
Pick Claude Fable 5.1 for coding: it scores 89.1 on the Vibe Coding Index against 75.8 for Gemini 3 Flash Preview. Pick Gemini 3 Flash Preview when output tokens cost 16.7x less, or when the context window is larger, 1.05M against 1M tokens.
Which is cheaper, Claude Fable 5.1 or Gemini 3 Flash Preview?
Claude Fable 5.1 costs $10.00 per million input tokens and $50.00 per million output tokens; Gemini 3 Flash Preview costs $0.50 and $3.00. Cost per solved task is known for Gemini 3 Flash Preview only.
Which has the bigger context window, Claude Fable 5.1 or Gemini 3 Flash Preview?
Gemini 3 Flash Preview, with 1.05M tokens against 1M.
How many benchmarks is the Claude Fable 5.1 vs Gemini 3 Flash Preview comparison based on?
46 benchmarks have a result for both models as of October 21, 2026. Claude Fable 5.1's coding index rests on 2 independent benchmarks and Gemini 3 Flash Preview's on 1. Where only one model has a result, the page says so instead of naming a winner.