Claude Fable 5.2 vs Gemini 3.8 Flash
Claude Fable 5.2 leads Gemini 3.8 Flash on coding, 87.8 to 60.3 on the Vibe Coding Index, and Gemini 3.8 Flash costs 10.7x less per output token ($3.75 vs $40.00 per million). Updated November 14, 2026; 65 benchmarks have a result for both.
vs boards won of 65 shared, 1 tied
Claude Fable 5.2 or Gemini 3.8 Flash: which to pick
Pick Claude Fable 5.2 for coding: it scores 87.8 on the Vibe Coding Index against 60.3 for Gemini 3.8 Flash, though on 4 benchmarks against 6.
Pick Gemini 3.8 Flash for output tokens 10.7x cheaper ($3.75 vs $40.00 per million) and a larger context window (1.05M against 1M tokens).
Model AClaude Fable 5.2Anthropic87.8/1004 independent benchmarksNo cost per solved taskModel BGemini 3.8 FlashGoogle60.3/1006 independent benchmarks$2.74 per solved task
- Shared results
- 65
- Claude Fable 5.2 only
- 3
- Gemini 3.8 Flash only
- 84
- 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 5.2
Claude Fable 5.2 scores 87.8 against 60.3.
4 and 6 benchmarks behind the scores
Intelligence
AA Intelligence Index
Claude Fable 5.2
Claude Fable 5.2 leads, 64.6 against 30.8.
Same board, both measured
Agentic work
AA Agentic Index
No call
Only Gemini 3.8 Flash has a AA Agentic Index result, 40.2.
Directional only
Reasoning
GPQA Diamond
No call
Only Gemini 3.8 Flash has a GPQA Diamond result, 94.4%.
Directional only
Knowledge
MMLU Pro
No call
Only Gemini 3.8 Flash has a MMLU Pro result, 90.2%.
Directional only
Web design
Design Arena: websites
Claude Fable 5.2
Claude Fable 5.2 leads, 1351 against 1291.
Same board, both measured
General
Vals Index
Claude Fable 5.2
Claude Fable 5.2 leads, 71.3% against 56.0%.
Same board, both measured
Long documents
Listed context window
Gemini 3.8 Flash
Gemini 3.8 Flash takes 1.05M tokens against 1M.
Listed by OpenRouter
Everyday cost
1K input + 500 output tokens
Gemini 3.8 Flash
Claude Fable 5.2 $0.028, Gemini 3.8 Flash $0.0026 per turn.
List prices
Cost per solved task
One SWE-bench Verified task, solved
No call
Only Gemini 3.8 Flash has the number, $2.74.
Directional only
At a glance
- Coding index
- Claude Fable 5.2 87.8 from 4 benchmarks, Gemini 3.8 Flash 60.3 from 6 benchmarks.
- Widest category
- Math, 41.9 points apart on average over 5 shared benchmarks.
- Widest single gap
- FrontierMath, tier 4: Claude Fable 5.2 100.0% against Gemini 3.8 Flash 22.0%, 78.0 points apart on a 0 to 100 scale.
- Output price
- Claude Fable 5.2 $40.00 against Gemini 3.8 Flash $3.75 per million output tokens, 10.7x apart.
- Context window
- Claude Fable 5.2 takes 1M tokens, Gemini 3.8 Flash 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 5.2 | Bars | Gemini 3.8 Flash | Ties |
|---|---|---|---|---|
| Coding | 14 | 0 | ||
| Intelligence | 2 | 0 | ||
| Agentic work | 12 | 2 | ||
| Reasoning | 10 | 2 | 1 tie | |
| Math | 5 | 0 | ||
| Knowledge | 3 | 1 | ||
| Web design | 6 | 0 | ||
| General | 6 | 1 | ||
| All shared boards | 58 | 6 | 1 tie |
CodingLike-for-likeSix of these boards feed the Vibe Coding Index140
| Benchmark | Claude Fable 5.2 | Gemini 3.8 Flash | Leader |
|---|---|---|---|
| LiveBench coding | 79.2% | 73.3% | Claude Fable 5.2 |
| LMArena WebDev | 1838 | 1583 | Claude Fable 5.2 |
| AA Coding Index | Not measured | 76.3 | Only Gemini 3.8 Flash measured |
| LiveCodeBench (Vals AI) | Not measured | 89.5% | Only Gemini 3.8 Flash measured |
| SWE-bench Verified (Vals AI) | Not measured | 80.0% | Only Gemini 3.8 Flash measured |
| Terminal-Bench 4 (Vals AI) | 65.2% | 19.7% | Claude Fable 5.2 |
| Vibe Code Bench (Vals AI) | 93.8% | 78.7% | Claude Fable 5.2 |
| Code migration (Vals AI) | Not measured | 36.5% | Only Gemini 3.8 Flash measured |
| ProgramBench (Vals AI) | 19.0% | 1.0% | Claude Fable 5.2 |
| IOI (Vals AI) | Not measured | 56.9% | Only Gemini 3.8 Flash measured |
| Terminal-Bench 2.1 (Vals AI) | Not measured | 81.3% | Only Gemini 3.8 Flash measured |
| SWE-bench Multimodal (Vals AI) | 62.3% | 40.8% | Claude Fable 5.2 |
| Vibe Code Bench 1-100 (Vals AI) | Not measured | 18.8% | Only Gemini 3.8 Flash measured |
| SkillsBench (Vals AI) | Not measured | 58.0% | Only Gemini 3.8 Flash measured |
| CyberBench (Vals AI) | Not measured | 43.8% | Only Gemini 3.8 Flash measured |
| SciCode | 67.7% | 56.6% | Claude Fable 5.2 |
| Terminal-Bench 4.0 (Artificial Analysis run) | 61.6% | 19.7% | Claude Fable 5.2 |
| FrontierCode 2.0 | 49.1% | 18.7% | Claude Fable 5.2 |
| FrontierCode | Not measured | 41.2% | Only Gemini 3.8 Flash measured |
| FrontierSWE | 69.9% | 19.6% | Claude Fable 5.2 |
| WeirdML | Not measured | 84.8% | Only Gemini 3.8 Flash measured |
| MirrorCode | Not measured | 38.9% | Only Gemini 3.8 Flash measured |
| ALE-Bench | 2509.8 | 1269.7 | Claude Fable 5.2 |
| LMArena Text: coding | Not measured | 1510 | Only Gemini 3.8 Flash measured |
| LMArena Text: software and IT | Not measured | 1509 | Only Gemini 3.8 Flash measured |
| LMArena WebDev: React | 1915 | 1575 | Claude Fable 5.2 |
| LMArena WebDev: HTML | 1738 | 1608 | Claude Fable 5.2 |
| LMArena WebDev: from an image | Not measured | 1594 | Only Gemini 3.8 Flash measured |
| SciCode | Not measured | 12.3% | Only Gemini 3.8 Flash measured |
| SWE-Bench Pro V2 | Not measured | 94.9% | Only Gemini 3.8 Flash measured |
| SWE Atlas: Codebase QnA | Not measured | 47.0% | Only Gemini 3.8 Flash measured |
| SWE Atlas: Refactoring | Not measured | 44.8% | Only Gemini 3.8 Flash measured |
| SWE Atlas: Test Writing | Not measured | 53.7% | Only Gemini 3.8 Flash measured |
| GameBench 2 | 99.1 | 64.0 | Claude Fable 5.2 |
| Terminal-Bench 4.0 | Not measured | 19.1% | Only Gemini 3.8 Flash measured |
| CursorBench 4.0 | 60.0% | Not measured | Only Claude Fable 5.2 measured |
| Neither model has a result on the other 16 boards here | |||
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index20
| Benchmark | Claude Fable 5.2 | Gemini 3.8 Flash | Leader |
|---|---|---|---|
| AA Intelligence Index | 64.6 | 30.8 | Claude Fable 5.2 |
| Epoch Capabilities Index | 173.4 | 158.8 | Claude Fable 5.2 |
Agentic workLike-for-likePublic boards, shown as published, kept out of the index122
| Benchmark | Claude Fable 5.2 | Gemini 3.8 Flash | Leader |
|---|---|---|---|
| AA Agentic Index | Not measured | 40.2 | Only Gemini 3.8 Flash measured |
| Design Arena: agents building web apps | Not measured | 1213 | Only Gemini 3.8 Flash measured |
| Design Arena: agents building full-stack apps | 1402 | 1217 | Claude Fable 5.2 |
| Design Arena: agents building mobile apps | 1325 | 1225 | Claude Fable 5.2 |
| Design Arena: agents building Android apps | Not measured | 1085 | Only Gemini 3.8 Flash measured |
| Design Arena: agents building Godot games | Not measured | 1248 | Only Gemini 3.8 Flash measured |
| Design Arena: PowerPoint slides | Not measured | 1150 | Only Gemini 3.8 Flash measured |
| Design Arena: spreadsheets | 1434 | 1034 | Claude Fable 5.2 |
| LiveBench research | 94.5% | 79.4% | Claude Fable 5.2 |
| LiveBench browser | 86.9% | 45.1% | Claude Fable 5.2 |
| LiveBench long agentic | 82.9% | 16.5% | Claude Fable 5.2 |
| SREBench (Vals AI) | Not measured | 11.1% | Only Gemini 3.8 Flash measured |
| Finance Agent (Vals AI) | Not measured | 61.4% | Only Gemini 3.8 Flash measured |
| Tax Agent Bench (Vals AI) | 32.1% | 32.1% | Gemini 3.8 Flash |
| Legal Research Bench (Vals AI) | 46.1% | 38.9% | Claude Fable 5.2 |
| Harvey's Legal Agent Benchmark (Vals AI) | 5.0% | 12.1% | Gemini 3.8 Flash |
| Excel Modeling Benchmark (Vals AI) | Not measured | 72.2% | Only Gemini 3.8 Flash measured |
| BioMysteryBench (Vals AI) | 83.7% | 62.2% | Claude Fable 5.2 |
| Terminal-Bench-Science (Vals AI) | 55.7% | 8.6% | Claude Fable 5.2 |
| Vals Science Index | 63.7% | 35.8% | Claude Fable 5.2 |
| Time Horizon Index (Vals AI) | Not measured | 18.8% | Only Gemini 3.8 Flash measured |
| CUA-bench (Vals AI) | Not measured | 4.2% | Only Gemini 3.8 Flash measured |
| APEX-Agents | 80.1% | 64.3% | Claude Fable 5.2 |
| Remote Labor Index | 41.3% | 5.8% | Claude Fable 5.2 |
| SpireClimb | 15.5% | Not measured | Only Claude Fable 5.2 measured |
| Vending-Bench 2 | Not measured | $5,094 | Only Gemini 3.8 Flash measured |
| Neither model has a result on the other 18 boards here | |||
ReasoningLike-for-likePublic boards, shown as published, kept out of the index102
| Benchmark | Claude Fable 5.2 | Gemini 3.8 Flash | Leader |
|---|---|---|---|
| GPQA Diamond | Not measured | 94.4% | Only Gemini 3.8 Flash measured |
| LiveBench reasoning | 88.8% | 89.3% | Gemini 3.8 Flash |
| MysteryMechanism (Vals AI) | 51.8% | 36.5% | Claude Fable 5.2 |
| MMMU Pro (Vals AI) | Not measured | 89.1% | Only Gemini 3.8 Flash measured |
| GPQA Diamond (Artificial Analysis run) | Not measured | 95.3% | Only Gemini 3.8 Flash measured |
| Humanity's Last Exam (Artificial Analysis run) | 74.3% | 47.8% | Claude Fable 5.2 |
| HLE-Diamond (Artificial Analysis run) | 80.2% | 33.1% | Claude Fable 5.2 |
| CritPt v2, hard subset (Artificial Analysis run) | 76.5% | 46.5% | Claude Fable 5.2 |
| GPQA Diamond (Epoch AI run) | 93.9% | 95.4% | Gemini 3.8 Flash |
| ARC-AGI | 98.5% | 98.5% | Tie |
| ARC-AGI-2 | 93.8% | 89.2% | Claude Fable 5.2 |
| SimpleBench | 94.9% | 82.4% | Claude Fable 5.2 |
| Chess puzzles | 79.0% | 58.0% | Claude Fable 5.2 |
| Mystery game puzzles | 90.0% | 47.0% | Claude Fable 5.2 |
| EBR-bench | 90.5% | Not measured | Only Claude Fable 5.2 measured |
| LMArena Text: hard prompts | Not measured | 1510 | Only Gemini 3.8 Flash measured |
| LMArena Text: expert | Not measured | 1527 | Only Gemini 3.8 Flash measured |
| LMArena Text: hard prompts in English | Not measured | 1508 | Only Gemini 3.8 Flash measured |
| LMArena Vision: diagrams | Not measured | 1353 | Only Gemini 3.8 Flash measured |
| LMArena Vision: homework | Not measured | 1351 | Only Gemini 3.8 Flash measured |
| Humanity's Last Exam (Scale run) | 72.4% | 34.3% | Claude Fable 5.2 |
| GoBench | 2566 | 1615 | Claude Fable 5.2 |
| Neither model has a result on the other 4 boards here | |||
MathLike-for-likePublic boards, shown as published, kept out of the index50
| Benchmark | Claude Fable 5.2 | Gemini 3.8 Flash | Leader |
|---|---|---|---|
| OTIS Mock AIME | 99.7% | 98.9% | Claude Fable 5.2 |
| FrontierMath, tiers 1 to 3 | 95.1% | 68.4% | Claude Fable 5.2 |
| FrontierMath, tier 4 | 100.0% | 22.0% | Claude Fable 5.2 |
| ProofBench | 100.0% | 48.0% | Claude Fable 5.2 |
| LMArena Text: math | Not measured | 1525 | Only Gemini 3.8 Flash measured |
| LMArena Text: mathematical work | Not measured | 1519 | Only Gemini 3.8 Flash measured |
| MathArena | 82.8% | 31.0% | Claude Fable 5.2 |
| Neither model has a result on the other 7 boards here | |||
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index31
| Benchmark | Claude Fable 5.2 | Gemini 3.8 Flash | Leader |
|---|---|---|---|
| MMLU Pro | Not measured | 90.2% | Only Gemini 3.8 Flash measured |
| LegalBench (Vals AI) | Not measured | 87.0% | Only Gemini 3.8 Flash measured |
| TaxEval (Vals AI) | Not measured | 74.5% | Only Gemini 3.8 Flash measured |
| MortgageTax (Vals AI) | Not measured | 65.3% | Only Gemini 3.8 Flash measured |
| MedCode (Vals AI) | Not measured | 48.1% | Only Gemini 3.8 Flash measured |
| AA-Omniscience | 66.8 | 23.7 | Claude Fable 5.2 |
| SimpleQA Verified | 94.0% | 69.7% | Claude Fable 5.2 |
| GeoBench | Not measured | 86.0% | Only Gemini 3.8 Flash measured |
| LMArena Text: science | Not measured | 1522 | Only Gemini 3.8 Flash measured |
| LMArena Text: medicine and healthcare | Not measured | 1507 | Only Gemini 3.8 Flash measured |
| LMArena Text: legal and government | Not measured | 1502 | Only Gemini 3.8 Flash measured |
| LMArena Text: business and finance | Not measured | 1483 | Only Gemini 3.8 Flash measured |
| FACTS Benchmark Suite | Not measured | 71.2% | Only Gemini 3.8 Flash measured |
| PRBench Finance | 47.1% | 49.5% | Gemini 3.8 Flash |
| PRBench Legal | 49.0% | 48.9% | Claude Fable 5.2 |
| Neither model has a result on the other 6 boards here | |||
Web designLike-for-likePublic boards, shown as published, kept out of the index60
| Benchmark | Claude Fable 5.2 | Gemini 3.8 Flash | Leader |
|---|---|---|---|
| Design Arena: websites | 1351 | 1291 | Claude Fable 5.2 |
| Design Arena: UI components | 1371 | 1304 | Claude Fable 5.2 |
| Design Arena: game dev | 1396 | 1296 | Claude Fable 5.2 |
| Design Arena: data viz | Not measured | 1276 | Only Gemini 3.8 Flash measured |
| Design Arena: 3D | 1517 | 1274 | Claude Fable 5.2 |
| Design Arena: all code categories | 1373 | 1292 | Claude Fable 5.2 |
| Design Arena: SVG | Not measured | 1290 | Only Gemini 3.8 Flash measured |
| Design Arena: ASCII art | Not measured | 1269 | Only Gemini 3.8 Flash measured |
| LiveBench design | 85.1% | 69.7% | Claude Fable 5.2 |
GeneralLike-for-likePublic boards, shown as published, kept out of the index61
| Benchmark | Claude Fable 5.2 | Gemini 3.8 Flash | Leader |
|---|---|---|---|
| Vals Index | 71.3% | 56.0% | Claude Fable 5.2 |
| LiveBench data analysis | 81.5% | 54.0% | Claude Fable 5.2 |
| Public Benefits Bench (Vals AI) | Not measured | 65.3% | Only Gemini 3.8 Flash measured |
| SAGE (Vals AI) | Not measured | 88.2% | Only Gemini 3.8 Flash measured |
| MedScribe (Vals AI) | Not measured | 84.5% | Only Gemini 3.8 Flash measured |
| Long context reasoning (AA-LCR) | 83.3% | 84.0% | Gemini 3.8 Flash |
| GDPval-AA | 1831 | 1442 | Claude Fable 5.2 |
| DTBench | 99.2% | 95.7% | Claude Fable 5.2 |
| LMCA | 70.6% | 52.9% | Claude Fable 5.2 |
| Surface Evolver Bench | Not measured | 76.9% | Only Gemini 3.8 Flash measured |
| Furniture assembly | 90.0% | 31.7% | Claude Fable 5.2 |
| LMArena Text | Not measured | 1500 | Only Gemini 3.8 Flash measured |
| LMArena Text: instruction following | Not measured | 1493 | Only Gemini 3.8 Flash measured |
| LMArena Text: creative writing | Not measured | 1493 | Only Gemini 3.8 Flash measured |
| LMArena Vision | Not measured | 1317 | Only Gemini 3.8 Flash measured |
| LMArena Text: English | Not measured | 1500 | Only Gemini 3.8 Flash measured |
| LMArena Text: non-English | Not measured | 1492 | Only Gemini 3.8 Flash measured |
| LMArena Text: Chinese | Not measured | 1557 | Only Gemini 3.8 Flash measured |
| LMArena Text: German | Not measured | 1503 | Only Gemini 3.8 Flash measured |
| LMArena Text: Japanese | Not measured | 1515 | Only Gemini 3.8 Flash measured |
| LMArena Text: Korean | Not measured | 1470 | Only Gemini 3.8 Flash measured |
| LMArena Text: French | Not measured | 1497 | Only Gemini 3.8 Flash measured |
| LMArena Text: Spanish | Not measured | 1486 | Only Gemini 3.8 Flash measured |
| LMArena Text: Russian | Not measured | 1516 | Only Gemini 3.8 Flash measured |
| LMArena Text: Polish | Not measured | 1509 | Only Gemini 3.8 Flash measured |
| LMArena Text: multi-turn | Not measured | 1503 | Only Gemini 3.8 Flash measured |
| LMArena Text: longer queries | Not measured | 1508 | Only Gemini 3.8 Flash measured |
| LMArena Text: writing and language | Not measured | 1496 | Only Gemini 3.8 Flash measured |
| LMArena Text: entertainment and media | Not measured | 1484 | Only Gemini 3.8 Flash measured |
| LMArena Vision: English | Not measured | 1315 | Only Gemini 3.8 Flash measured |
| LMArena Vision: Chinese | Not measured | 1411 | Only Gemini 3.8 Flash measured |
| LMArena Vision: reading text | Not measured | 1332 | Only Gemini 3.8 Flash measured |
| LMArena Vision: humor | Not measured | 1329 | Only Gemini 3.8 Flash measured |
| LMArena Vision: creative writing | Not measured | 1320 | Only Gemini 3.8 Flash measured |
| LMArena Document | Not measured | 1482 | Only Gemini 3.8 Flash measured |
| Neither model has a result on the other 14 boards here | |||
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
| Benchmark | Claude Fable 5.2 | Gemini 3.8 Flash | 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 5.2$0.028Fits in one request
Gemini 3.8 Flash$0.0026Fits in one request
Gemini 3.8 Flash costs less
Repository review
50K input + 3K output tokens
Claude Fable 5.2$0.520Fits in one request
Gemini 3.8 Flash$0.049Fits in one request
Gemini 3.8 Flash costs less
Agent loop
200K input + 10K output tokens
Claude Fable 5.2$2.00Fits in one request
Gemini 3.8 Flash$0.188Fits in one request
Gemini 3.8 Flash 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 5.2 | Google Gemini 3.8 Flash |
|---|---|---|
| Maker | Anthropic | |
| Weights | No public weights listed | No public weights listed |
| Released | November 9, 2026 | September 2, 2026 |
| Context window | 1M | 1.05M |
| Input $/Mtok | $8.00 | $0.75 |
| Output $/Mtok | $40.00 | $3.75 |
| Coding index | 87.8 | 60.3 |
| Independent measurements behind it | 4 | 6 |
| Cost per solved task | Not computable | $2.74 |
| Source | OpenRouter listing | OpenRouter listing |
Questions
Is Claude Fable 5.2 better than Gemini 3.8 Flash for coding?
Pick Claude Fable 5.2 for coding: it scores 87.8 on the Vibe Coding Index against 60.3 for Gemini 3.8 Flash, though on 4 benchmarks against 6. Pick Gemini 3.8 Flash for output tokens 10.7x cheaper ($3.75 vs $40.00 per million) and a larger context window (1.05M against 1M tokens).
Which is cheaper, Claude Fable 5.2 or Gemini 3.8 Flash?
Claude Fable 5.2 costs $8.00 per million input tokens and $40.00 per million output tokens; Gemini 3.8 Flash costs $0.75 and $3.75. Cost per solved task is known for Gemini 3.8 Flash only.
Which has the bigger context window, Claude Fable 5.2 or Gemini 3.8 Flash?
Gemini 3.8 Flash, with 1.05M tokens against 1M.
How many benchmarks is the Claude Fable 5.2 vs Gemini 3.8 Flash comparison based on?
65 benchmarks have a result for both models as of November 14, 2026. Claude Fable 5.2's coding index rests on 4 independent benchmarks and Gemini 3.8 Flash's on 6. Where only one model has a result, the page says so instead of naming a winner.