LLMBenchmark.ai

Enter opens the highlighted result. Esc closes.

Claude Fable 5.1 vs Gemini 3.5 Flash

Updated October 21, 2026. 97 benchmarks have a result for both. Coding is ranked on the Vibe Coding Index; every other board is shown as published.

Replace Claude Fable 5.1 Replace Gemini 3.5 Flash
Claude Fable 5.1Anthropic
Coding
89.1
Overall
53.4
Output $/M
$50.00
94
Gemini 3.5 FlashGoogle
Coding
42.8
Overall
33.6
Output $/M
$9.00
3
vs boards won of 97 shared

Decision reading

Pick Claude Fable 5.1 for coding: it scores 89.1 on the Vibe Coding Index against 42.8 for Gemini 3.5 Flash.

Pick Gemini 3.5 Flash when output tokens cost 5.6x 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 3.5 FlashGoogle42.8/1001 independent benchmark$1.21 per solved task
Shared results
97
Claude Fable 5.1 only
27
Gemini 3.5 Flash only
13
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.

At a glance

Coding index
Claude Fable 5.1 89.1 from 2 benchmarks, Gemini 3.5 Flash 42.8 from 1 benchmark.
Widest category
Math, 29.0 points apart on average over 6 shared benchmarks.
Widest single gap
ProofBench: Claude Fable 5.1 100.0% against Gemini 3.5 Flash 31.0%, 69.0 points apart on a 0 to 100 scale.
Output price
Claude Fable 5.1 $50.00 against Gemini 3.5 Flash $9.00 per million output tokens, 5.6x apart.
Context window
Claude Fable 5.1 takes 1M tokens, Gemini 3.5 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.

Boards won, where both have a result
CategoryClaude Fable 5.1BarsGemini 3.5 FlashTies
Coding160
Intelligence20
Agentic work120
Reasoning140
Math60
Knowledge91
Web design80
General272
All shared boards943
CodingLike-for-likeFour of these boards feed the Vibe Coding Index160
Coding benchmarks for Claude Fable 5.1 and Gemini 3.5 Flash
BenchmarkClaude Fable 5.1Gemini 3.5 FlashLeader
LiveBench coding97.7%Not measuredOnly Claude Fable 5.1 measured
LMArena WebDev17431499Claude Fable 5.1
AA Coding Index81.6Not measuredOnly Claude Fable 5.1 measured
LiveCodeBench (Vals AI)90.5%87.6%Claude Fable 5.1
SWE-bench Verified (Vals AI)Not measured78.8%Only Gemini 3.5 Flash measured
Terminal-Bench 4 (Vals AI)58.1%6.1%Claude Fable 5.1
Vibe Code Bench (Vals AI)90.3%48.7%Claude Fable 5.1
Code migration (Vals AI)54.6%26.8%Claude Fable 5.1
ProgramBench (Vals AI)7.0%0.0%Claude Fable 5.1
IOI (Vals AI)90.8%Not measuredOnly Claude Fable 5.1 measured
Terminal-Bench 2.1 (Vals AI)85.0%74.2%Claude Fable 5.1
SWE-bench Multimodal (Vals AI)61.3%Not measuredOnly Claude Fable 5.1 measured
Vibe Code Bench 1-100 (Vals AI)28.0%Not measuredOnly Claude Fable 5.1 measured
SkillsBench (Vals AI)61.5%52.7%Claude Fable 5.1
CyberBench (Vals AI)70.4%Not measuredOnly Claude Fable 5.1 measured
SciCode63.1%53.9%Claude Fable 5.1
Terminal-Bench Hard (Artificial Analysis run)Not measured46.2%Only Gemini 3.5 Flash measured
FrontierCode50.9%Not measuredOnly Claude Fable 5.1 measured
FrontierSWE56.3%Not measuredOnly Claude Fable 5.1 measured
GSO-Bench88.2%Not measuredOnly Claude Fable 5.1 measured
WeirdML92.9%62.6%Claude Fable 5.1
MirrorCode73.3%Not measuredOnly Claude Fable 5.1 measured
ALE-Bench2143.2911.0Claude Fable 5.1
LMArena Text: coding15321493Claude Fable 5.1
LMArena Text: software and IT15301494Claude Fable 5.1
LMArena WebDev: React17921495Claude Fable 5.1
LMArena WebDev: HTML16841522Claude Fable 5.1
LMArena WebDev: from an image17221504Claude Fable 5.1
Neither model has a result on the other 10 boards here
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index20
Intelligence benchmarks for Claude Fable 5.1 and Gemini 3.5 Flash
BenchmarkClaude Fable 5.1Gemini 3.5 FlashLeader
AA Intelligence Index53.433.6Claude Fable 5.1
Epoch Capabilities Index166.5154.9Claude Fable 5.1
Agentic workLike-for-likePublic boards, shown as published, kept out of the index120
Agentic work benchmarks for Claude Fable 5.1 and Gemini 3.5 Flash
BenchmarkClaude Fable 5.1Gemini 3.5 FlashLeader
AA Agentic Index57.9Not measuredOnly Claude Fable 5.1 measured
Design Arena: agents building web apps13181202Claude Fable 5.1
Design Arena: agents building full-stack apps13261197Claude Fable 5.1
Design Arena: agents building mobile apps12671175Claude Fable 5.1
Design Arena: agents building Android appsNot measured1190Only Gemini 3.5 Flash measured
Design Arena: agents building Godot games13271098Claude Fable 5.1
Design Arena: agents building gamesNot measured1180Only Gemini 3.5 Flash measured
Design Arena: HTML slidesNot measured1142Only Gemini 3.5 Flash measured
Design Arena: PowerPoint slides13281178Claude Fable 5.1
Design Arena: spreadsheets1374Not measuredOnly Claude Fable 5.1 measured
LiveBench research82.0%Not measuredOnly Claude Fable 5.1 measured
LiveBench browser100.0%Not measuredOnly Claude Fable 5.1 measured
LiveBench long agentic80.8%Not measuredOnly Claude Fable 5.1 measured
SREBench (Vals AI)22.9%Not measuredOnly Claude Fable 5.1 measured
Finance Agent (Vals AI)58.9%57.9%Claude Fable 5.1
Tax Agent Bench (Vals AI)49.2%21.6%Claude Fable 5.1
Legal Research Bench (Vals AI)55.3%30.8%Claude Fable 5.1
Excel Modeling Benchmark (Vals AI)76.7%63.5%Claude Fable 5.1
Terminal-Bench-Science (Vals AI)40.0%5.7%Claude Fable 5.1
Time Horizon Index (Vals AI)63.3%Not measuredOnly Claude Fable 5.1 measured
CUA-bench (Vals AI)13.2%Not measuredOnly Claude Fable 5.1 measured
Robo-bench (Vals AI)5.8%Not measuredOnly Claude Fable 5.1 measured
τ²-Bench TelecomNot measured95.6%Only Gemini 3.5 Flash measured
APEX-Agents68.6%27.5%Claude Fable 5.1
Remote Labor Index17.9%Not measuredOnly Claude Fable 5.1 measured
SpireClimb2.0%Not measuredOnly Claude Fable 5.1 measured
Vending-Bench 2$5,422$5,396Claude Fable 5.1
LMArena Search1246Not measuredOnly 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 index140
Reasoning benchmarks for Claude Fable 5.1 and Gemini 3.5 Flash
BenchmarkClaude Fable 5.1Gemini 3.5 FlashLeader
GPQA Diamond93.4%92.7%Claude Fable 5.1
LiveBench reasoning91.7%Not measuredOnly Claude Fable 5.1 measured
MysteryMechanism (Vals AI)47.8%Not measuredOnly Claude Fable 5.1 measured
MMMU Pro (Vals AI)90.6%88.3%Claude Fable 5.1
GPQA Diamond (Artificial Analysis run)93.7%92.2%Claude Fable 5.1
Humanity's Last Exam (Artificial Analysis run)59.1%42.7%Claude Fable 5.1
GPQA Diamond (Epoch AI run)Not measured92.8%Only Gemini 3.5 Flash measured
ARC-AGI97.5%92.5%Claude Fable 5.1
ARC-AGI-290.0%72.1%Claude Fable 5.1
SimpleBenchNot measured76.7%Only Gemini 3.5 Flash measured
Chess puzzles48.0%45.0%Claude Fable 5.1
Mystery game puzzles58.0%32.0%Claude Fable 5.1
EBR-bench57.1%4.8%Claude Fable 5.1
LMArena Text: hard prompts15281488Claude Fable 5.1
LMArena Text: expert15441495Claude Fable 5.1
LMArena Text: hard prompts in English15221483Claude Fable 5.1
LMArena Vision: diagrams13431323Claude Fable 5.1
LMArena Vision: homework13451330Claude Fable 5.1
Neither model has a result on the other 3 boards here
MathLike-for-likePublic boards, shown as published, kept out of the index60
Math benchmarks for Claude Fable 5.1 and Gemini 3.5 Flash
BenchmarkClaude Fable 5.1Gemini 3.5 FlashLeader
OTIS Mock AIME100.0%95.6%Claude Fable 5.1
FrontierMath, tiers 1 to 390.2%62.8%Claude Fable 5.1
FrontierMath, tier 487.8%26.8%Claude Fable 5.1
ProofBench100.0%31.0%Claude Fable 5.1
LMArena Text: math15311504Claude Fable 5.1
LMArena Text: mathematical work15411495Claude Fable 5.1
Neither model has a result on the other 7 boards here
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index91
Knowledge benchmarks for Claude Fable 5.1 and Gemini 3.5 Flash
BenchmarkClaude Fable 5.1Gemini 3.5 FlashLeader
MMLU Pro92.4%89.5%Claude Fable 5.1
LegalBench (Vals AI)88.5%83.6%Claude Fable 5.1
CorpFin (Vals AI)Not measured64.7%Only Gemini 3.5 Flash measured
TaxEval (Vals AI)76.0%74.4%Claude Fable 5.1
MortgageTax (Vals AI)70.8%68.1%Claude Fable 5.1
MedCode (Vals AI)53.5%55.8%Gemini 3.5 Flash
SimpleQA Verified70.8%66.2%Claude Fable 5.1
LMArena Text: science15321495Claude Fable 5.1
LMArena Text: medicine and healthcare15311483Claude Fable 5.1
LMArena Text: legal and government15141488Claude Fable 5.1
LMArena Text: business and finance14931467Claude Fable 5.1
Neither model has a result on the other 6 boards here
Web designLike-for-likePublic boards, shown as published, kept out of the index80
Web design benchmarks for Claude Fable 5.1 and Gemini 3.5 Flash
BenchmarkClaude Fable 5.1Gemini 3.5 FlashLeader
Design Arena: websites13131268Claude Fable 5.1
Design Arena: UI components13381272Claude Fable 5.1
Design Arena: game dev13821263Claude Fable 5.1
Design Arena: data viz13441236Claude Fable 5.1
Design Arena: 3D13931244Claude Fable 5.1
Design Arena: all code categories13361266Claude Fable 5.1
Design Arena: SVG13011254Claude Fable 5.1
Design Arena: ASCII art13241253Claude Fable 5.1
LiveBench design83.4%Not measuredOnly Claude Fable 5.1 measured
GeneralLike-for-likePublic boards, shown as published, kept out of the index272
General benchmarks for Claude Fable 5.1 and Gemini 3.5 Flash
BenchmarkClaude Fable 5.1Gemini 3.5 FlashLeader
LiveBench data analysis80.3%Not measuredOnly Claude Fable 5.1 measured
Public Benefits Bench (Vals AI)74.9%59.5%Claude Fable 5.1
SAGE (Vals AI)48.5%49.9%Gemini 3.5 Flash
MedScribe (Vals AI)91.3%76.6%Claude Fable 5.1
Vals Multimodal IndexNot measured62.9%Only Gemini 3.5 Flash measured
IFBenchNot measured76.3%Only Gemini 3.5 Flash measured
Long context reasoning (AA-LCR)85.3%74.3%Claude Fable 5.1
DTBench97.6%94.7%Claude Fable 5.1
LMCA65.5%47.1%Claude Fable 5.1
Surface Evolver BenchNot measured58.1%Only Gemini 3.5 Flash measured
Furniture assembly70.0%Not measuredOnly Claude Fable 5.1 measured
LMArena Text15121482Claude Fable 5.1
LMArena Text: instruction following15181467Claude Fable 5.1
LMArena Text: creative writing15091470Claude Fable 5.1
LMArena Vision13191308Claude Fable 5.1
LMArena Text: English15061481Claude Fable 5.1
LMArena Text: non-English15081475Claude Fable 5.1
LMArena Text: Chinese15841527Claude Fable 5.1
LMArena Text: German14991494Claude Fable 5.1
LMArena Text: Japanese15621486Claude Fable 5.1
LMArena Text: Korean15171448Claude Fable 5.1
LMArena Text: French15231490Claude Fable 5.1
LMArena Text: Spanish15201480Claude Fable 5.1
LMArena Text: Russian15201493Claude Fable 5.1
LMArena Text: Polish15251516Claude Fable 5.1
LMArena Text: multi-turn14931481Claude Fable 5.1
LMArena Text: longer queries15241483Claude Fable 5.1
LMArena Text: writing and language15101478Claude Fable 5.1
LMArena Text: entertainment and media14971459Claude Fable 5.1
LMArena Vision: English13131305Claude Fable 5.1
LMArena Vision: Chinese13911377Claude Fable 5.1
LMArena Vision: reading text13271317Claude Fable 5.1
LMArena Vision: humor13181321Gemini 3.5 Flash
LMArena Vision: creative writing13301301Claude Fable 5.1
LMArena DocumentNot measured1463Only Gemini 3.5 Flash 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
Image generation benchmarks for Claude Fable 5.1 and Gemini 3.5 Flash
BenchmarkClaude Fable 5.1Gemini 3.5 FlashLeader
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 3.5 Flash$0.0060Fits in one request

Gemini 3.5 Flash costs less

Repository review

50K input + 3K output tokens

Claude Fable 5.1$0.650Fits in one request
Gemini 3.5 Flash$0.102Fits in one request

Gemini 3.5 Flash costs less

Agent loop

200K input + 10K output tokens

Claude Fable 5.1$2.50Fits in one request
Gemini 3.5 Flash$0.390Fits in one request

Gemini 3.5 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.

Specifications of Claude Fable 5.1 and Gemini 3.5 Flash
SpecificationAnthropic Claude Fable 5.1Google Gemini 3.5 Flash
MakerAnthropicGoogle
WeightsNo public weights listedNo public weights listed
ReleasedSeptember 1, 2026May 19, 2026
Context window1M1.05M
Input $/Mtok$10.00$1.50
Output $/Mtok$50.00$9.00
Coding index89.142.8
Independent measurements behind it21
Cost per solved taskNot computable$1.21
SourceOpenRouter listingOpenRouter listing

Questions

Is Claude Fable 5.1 better than Gemini 3.5 Flash for coding?

Pick Claude Fable 5.1 for coding: it scores 89.1 on the Vibe Coding Index against 42.8 for Gemini 3.5 Flash. Pick Gemini 3.5 Flash when output tokens cost 5.6x less, or when the context window is larger, 1.05M against 1M tokens.

Which is cheaper, Claude Fable 5.1 or Gemini 3.5 Flash?

Claude Fable 5.1 costs $10.00 per million input tokens and $50.00 per million output tokens; Gemini 3.5 Flash costs $1.50 and $9.00. Cost per solved task is known for Gemini 3.5 Flash only.

Which has the bigger context window, Claude Fable 5.1 or Gemini 3.5 Flash?

Gemini 3.5 Flash, with 1.05M tokens against 1M.

How many benchmarks is the Claude Fable 5.1 vs Gemini 3.5 Flash comparison based on?

97 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 3.5 Flash's on 1. Where only one model has a result, the page says so instead of naming a winner.

Compare next