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Claude Fable 5.1 vs Gemini 3.5 Flash Lite

Updated October 21, 2026. 80 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 Lite
Claude Fable 5.1Anthropic
Coding
89.1
Overall
53.4
Output $/M
$50.00
80
Gemini 3.5 Flash LiteGoogle
Coding
33.6
Overall
22.2
Output $/M
$2.50
0
vs boards won of 80 shared

Decision reading

Pick Claude Fable 5.1 for coding: it scores 89.1 on the Vibe Coding Index against 33.6 for Gemini 3.5 Flash Lite.

Pick Gemini 3.5 Flash Lite when output tokens cost 20.0x 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 Flash LiteGoogle33.6/1001 independent benchmark$0.41 per solved task
Shared results
80
Claude Fable 5.1 only
44
Gemini 3.5 Flash Lite only
3
Like-for-like categories
7 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 Lite 33.6 from 1 benchmark.
Widest category
Math, 50.3 points apart on average over 6 shared benchmarks.
Widest single gap
FrontierMath, tier 4: Claude Fable 5.1 87.8% against Gemini 3.5 Flash Lite 0.0%, 87.8 points apart on a 0 to 100 scale.
Output price
Claude Fable 5.1 $50.00 against Gemini 3.5 Flash Lite $2.50 per million output tokens, 20.0x apart.
Context window
Claude Fable 5.1 takes 1M tokens, Gemini 3.5 Flash Lite 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 Flash LiteTies
Coding150
Intelligence20
Agentic work60
Reasoning130
Math60
Knowledge90
General290
All shared boards800
CodingLike-for-likeFour of these boards feed the Vibe Coding Index150
Coding benchmarks for Claude Fable 5.1 and Gemini 3.5 Flash Lite
BenchmarkClaude Fable 5.1Gemini 3.5 Flash LiteLeader
LiveBench coding97.7%Not measuredOnly Claude Fable 5.1 measured
LMArena WebDev17431435Claude Fable 5.1
AA Coding Index81.649.3Claude Fable 5.1
LiveCodeBench (Vals AI)90.5%79.0%Claude Fable 5.1
SWE-bench Verified (Vals AI)Not measured75.0%Only Gemini 3.5 Flash Lite measured
Terminal-Bench 4 (Vals AI)58.1%Not measuredOnly Claude Fable 5.1 measured
Vibe Code Bench (Vals AI)90.3%37.2%Claude Fable 5.1
Code migration (Vals AI)54.6%6.2%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%50.2%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%Not measuredOnly Claude Fable 5.1 measured
CyberBench (Vals AI)70.4%59.1%Claude Fable 5.1
SciCode63.1%41.3%Claude Fable 5.1
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%39.0%Claude Fable 5.1
MirrorCode73.3%Not measuredOnly Claude Fable 5.1 measured
ALE-Bench2143.2765.3Claude Fable 5.1
LMArena Text: coding15321453Claude Fable 5.1
LMArena Text: software and IT15301451Claude Fable 5.1
LMArena WebDev: React17921408Claude Fable 5.1
LMArena WebDev: HTML1684Not measuredOnly Claude Fable 5.1 measured
LMArena WebDev: from an image17221448Claude Fable 5.1
Neither model has a result on the other 11 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 Lite
BenchmarkClaude Fable 5.1Gemini 3.5 Flash LiteLeader
AA Intelligence Index53.422.2Claude Fable 5.1
Epoch Capabilities Index166.5144.9Claude Fable 5.1
Agentic workLike-for-likePublic boards, shown as published, kept out of the index60
Agentic work benchmarks for Claude Fable 5.1 and Gemini 3.5 Flash Lite
BenchmarkClaude Fable 5.1Gemini 3.5 Flash LiteLeader
AA Agentic Index57.914.3Claude Fable 5.1
Design Arena: agents building web apps1318Not measuredOnly Claude Fable 5.1 measured
Design Arena: agents building full-stack apps1326Not measuredOnly Claude Fable 5.1 measured
Design Arena: agents building mobile apps1267Not measuredOnly Claude Fable 5.1 measured
Design Arena: agents building Godot games1327Not measuredOnly Claude Fable 5.1 measured
Design Arena: PowerPoint slides1328Not measuredOnly Claude Fable 5.1 measured
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%47.4%Claude Fable 5.1
Tax Agent Bench (Vals AI)49.2%7.2%Claude Fable 5.1
Legal Research Bench (Vals AI)55.3%13.9%Claude Fable 5.1
Excel Modeling Benchmark (Vals AI)76.7%43.2%Claude Fable 5.1
Terminal-Bench-Science (Vals AI)40.0%Not measuredOnly Claude Fable 5.1 measured
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
APEX-Agents68.6%29.3%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$5,422Not measuredOnly Claude Fable 5.1 measured
LMArena Search1246Not measuredOnly 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 index130
Reasoning benchmarks for Claude Fable 5.1 and Gemini 3.5 Flash Lite
BenchmarkClaude Fable 5.1Gemini 3.5 Flash LiteLeader
GPQA Diamond93.4%83.8%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%83.6%Claude Fable 5.1
GPQA Diamond (Artificial Analysis run)93.7%83.8%Claude Fable 5.1
Humanity's Last Exam (Artificial Analysis run)59.1%18.8%Claude Fable 5.1
GPQA Diamond (Epoch AI run)Not measured83.3%Only Gemini 3.5 Flash Lite measured
ARC-AGI97.5%53.5%Claude Fable 5.1
ARC-AGI-290.0%10.3%Claude Fable 5.1
Chess puzzles48.0%21.0%Claude Fable 5.1
Mystery game puzzles58.0%19.0%Claude Fable 5.1
EBR-bench57.1%Not measuredOnly Claude Fable 5.1 measured
LMArena Text: hard prompts15281441Claude Fable 5.1
LMArena Text: expert15441434Claude Fable 5.1
LMArena Text: hard prompts in English15221440Claude Fable 5.1
LMArena Vision: diagrams13431284Claude Fable 5.1
LMArena Vision: homework13451291Claude Fable 5.1
Neither model has a result on the other 4 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 Lite
BenchmarkClaude Fable 5.1Gemini 3.5 Flash LiteLeader
OTIS Mock AIME100.0%71.1%Claude Fable 5.1
FrontierMath, tiers 1 to 390.2%26.0%Claude Fable 5.1
FrontierMath, tier 487.8%0.0%Claude Fable 5.1
ProofBench100.0%13.0%Claude Fable 5.1
LMArena Text: math15311434Claude Fable 5.1
LMArena Text: mathematical work15411433Claude 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 index90
Knowledge benchmarks for Claude Fable 5.1 and Gemini 3.5 Flash Lite
BenchmarkClaude Fable 5.1Gemini 3.5 Flash LiteLeader
MMLU Pro92.4%85.8%Claude Fable 5.1
LegalBench (Vals AI)88.5%84.1%Claude Fable 5.1
CorpFin (Vals AI)Not measured60.7%Only Gemini 3.5 Flash Lite measured
TaxEval (Vals AI)76.0%72.6%Claude Fable 5.1
MortgageTax (Vals AI)70.8%68.7%Claude Fable 5.1
MedCode (Vals AI)53.5%43.5%Claude Fable 5.1
SimpleQA Verified70.8%Not measuredOnly Claude Fable 5.1 measured
LMArena Text: science15321451Claude Fable 5.1
LMArena Text: medicine and healthcare15311438Claude Fable 5.1
LMArena Text: legal and government15141431Claude Fable 5.1
LMArena Text: business and finance14931423Claude Fable 5.1
Neither model has a result on the other 6 boards here
Web designDirectional onlyPublic boards, shown as published, kept out of the index9 boards, none shared
Web design benchmarks for Claude Fable 5.1 and Gemini 3.5 Flash Lite
BenchmarkClaude Fable 5.1Gemini 3.5 Flash LiteLeader
Design Arena: websites1313Not measuredOnly Claude Fable 5.1 measured
Design Arena: UI components1338Not measuredOnly Claude Fable 5.1 measured
Design Arena: game dev1382Not measuredOnly Claude Fable 5.1 measured
Design Arena: data viz1344Not measuredOnly Claude Fable 5.1 measured
Design Arena: 3D1393Not measuredOnly Claude Fable 5.1 measured
Design Arena: all code categories1336Not measuredOnly Claude Fable 5.1 measured
Design Arena: SVG1301Not measuredOnly Claude Fable 5.1 measured
Design Arena: ASCII art1324Not measuredOnly Claude Fable 5.1 measured
LiveBench design83.4%Not measuredOnly Claude Fable 5.1 measured
GeneralLike-for-likePublic boards, shown as published, kept out of the index290
General benchmarks for Claude Fable 5.1 and Gemini 3.5 Flash Lite
BenchmarkClaude Fable 5.1Gemini 3.5 Flash LiteLeader
LiveBench data analysis80.3%Not measuredOnly Claude Fable 5.1 measured
Public Benefits Bench (Vals AI)74.9%51.8%Claude Fable 5.1
SAGE (Vals AI)48.5%47.3%Claude Fable 5.1
MedScribe (Vals AI)91.3%70.9%Claude Fable 5.1
Long context reasoning (AA-LCR)85.3%76.0%Claude Fable 5.1
DTBench97.6%83.5%Claude Fable 5.1
LMCA65.5%37.6%Claude Fable 5.1
Furniture assembly70.0%Not measuredOnly Claude Fable 5.1 measured
LMArena Text15121435Claude Fable 5.1
LMArena Text: instruction following15181419Claude Fable 5.1
LMArena Text: creative writing15091421Claude Fable 5.1
LMArena Vision13191269Claude Fable 5.1
LMArena Text: English15061438Claude Fable 5.1
LMArena Text: non-English15081427Claude Fable 5.1
LMArena Text: Chinese15841468Claude Fable 5.1
LMArena Text: German14991454Claude Fable 5.1
LMArena Text: Japanese15621426Claude Fable 5.1
LMArena Text: Korean15171407Claude Fable 5.1
LMArena Text: French15231451Claude Fable 5.1
LMArena Text: Spanish15201441Claude Fable 5.1
LMArena Text: Russian15201443Claude Fable 5.1
LMArena Text: Polish15251437Claude Fable 5.1
LMArena Text: multi-turn14931445Claude Fable 5.1
LMArena Text: longer queries15241435Claude Fable 5.1
LMArena Text: writing and language15101428Claude Fable 5.1
LMArena Text: entertainment and media14971414Claude Fable 5.1
LMArena Vision: English13131269Claude Fable 5.1
LMArena Vision: Chinese13911311Claude Fable 5.1
LMArena Vision: reading text13271280Claude Fable 5.1
LMArena Vision: humor13181287Claude Fable 5.1
LMArena Vision: creative writing13301260Claude Fable 5.1
Neither model has a result on the other 15 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 Lite
BenchmarkClaude Fable 5.1Gemini 3.5 Flash LiteLeader
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 Lite$0.0015Fits in one request

Gemini 3.5 Flash Lite costs less

Repository review

50K input + 3K output tokens

Claude Fable 5.1$0.650Fits in one request
Gemini 3.5 Flash Lite$0.022Fits in one request

Gemini 3.5 Flash Lite costs less

Agent loop

200K input + 10K output tokens

Claude Fable 5.1$2.50Fits in one request
Gemini 3.5 Flash Lite$0.085Fits in one request

Gemini 3.5 Flash Lite 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 Lite
SpecificationAnthropic Claude Fable 5.1Google Gemini 3.5 Flash Lite
MakerAnthropicGoogle
WeightsNo public weights listedNo public weights listed
ReleasedSeptember 1, 2026July 21, 2026
Context window1M1.05M
Input $/Mtok$10.00$0.30
Output $/Mtok$50.00$2.50
Coding index89.133.6
Independent measurements behind it21
Cost per solved taskNot computable$0.41
SourceOpenRouter listingOpenRouter listing

Questions

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

Pick Claude Fable 5.1 for coding: it scores 89.1 on the Vibe Coding Index against 33.6 for Gemini 3.5 Flash Lite. Pick Gemini 3.5 Flash Lite when output tokens cost 20.0x 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 Lite?

Claude Fable 5.1 costs $10.00 per million input tokens and $50.00 per million output tokens; Gemini 3.5 Flash Lite costs $0.30 and $2.50. Cost per solved task is known for Gemini 3.5 Flash Lite only.

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

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

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

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

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