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Claude Fable 5 vs Gemini 3.5 Flash

Updated October 21, 2026. 109 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 Replace Gemini 3.5 Flash
Claude Fable 5Anthropic
Coding
82.1
Overall
49.6
Output $/M
$50.00
102
Gemini 3.5 FlashGoogle
Coding
42.8
Overall
33.6
Output $/M
$9.00
7
vs boards won of 109 shared

Decision reading

Pick Claude Fable 5 for coding: it scores 82.1 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 a solved task costs $1.21 against $2.16.

Model AClaude Fable 5Anthropic82.1/1002 independent benchmarks$2.16 per solved taskModel BGemini 3.5 FlashGoogle42.8/1001 independent benchmark$1.21 per solved task
Shared results
109
Claude Fable 5 only
17
Gemini 3.5 Flash only
1
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 82.1 from 2 benchmarks, Gemini 3.5 Flash 42.8 from 1 benchmark.
Widest category
Math, 26.9 points apart on average over 6 shared benchmarks.
Widest single gap
ProofBench: Claude Fable 5 95.0% against Gemini 3.5 Flash 31.0%, 64.0 points apart on a 0 to 100 scale.
Output price
Claude Fable 5 $50.00 against Gemini 3.5 Flash $9.00 per million output tokens, 5.6x apart.
Context window
Claude Fable 5 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 5BarsGemini 3.5 FlashTies
Coding170
Intelligence20
Agentic work151
Reasoning151
Math60
Knowledge101
Web design80
General294
All shared boards1027
CodingLike-for-likeFour of these boards feed the Vibe Coding Index170
Coding benchmarks for Claude Fable 5 and Gemini 3.5 Flash
BenchmarkClaude Fable 5Gemini 3.5 FlashLeader
LiveBench coding98.3%Not measuredOnly Claude Fable 5 measured
LMArena WebDev16241499Claude Fable 5
AA Coding Index76.5Not measuredOnly Claude Fable 5 measured
LiveCodeBench (Vals AI)89.8%87.6%Claude Fable 5
SWE-bench Verified (Vals AI)95.0%78.8%Claude Fable 5
Terminal-Bench 4 (Vals AI)41.4%6.1%Claude Fable 5
Vibe Code Bench (Vals AI)90.3%48.7%Claude Fable 5
Code migration (Vals AI)55.1%26.8%Claude Fable 5
ProgramBench (Vals AI)2.0%0.0%Claude Fable 5
Terminal-Bench 2.1 (Vals AI)80.5%74.2%Claude Fable 5
SkillsBench (Vals AI)Not measured52.7%Only Gemini 3.5 Flash measured
SciCode61.0%53.9%Claude Fable 5
Terminal-Bench Hard (Artificial Analysis run)62.9%46.2%Claude Fable 5
FrontierCode53.5%Not measuredOnly Claude Fable 5 measured
FrontierSWE47.0%Not measuredOnly Claude Fable 5 measured
GSO-Bench78.4%Not measuredOnly Claude Fable 5 measured
WeirdML91.9%62.6%Claude Fable 5
MirrorCode63.9%Not measuredOnly Claude Fable 5 measured
ALE-Bench2041.3911.0Claude Fable 5
LMArena Text: coding15181493Claude Fable 5
LMArena Text: software and IT15131494Claude Fable 5
LMArena WebDev: React16311495Claude Fable 5
LMArena WebDev: HTML16511522Claude Fable 5
LMArena WebDev: from an image16231504Claude Fable 5
Neither model has a result on the other 14 boards here
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index20
Intelligence benchmarks for Claude Fable 5 and Gemini 3.5 Flash
BenchmarkClaude Fable 5Gemini 3.5 FlashLeader
AA Intelligence Index49.633.6Claude Fable 5
Epoch Capabilities Index163.4154.9Claude Fable 5
Agentic workLike-for-likePublic boards, shown as published, kept out of the index151
Agentic work benchmarks for Claude Fable 5 and Gemini 3.5 Flash
BenchmarkClaude Fable 5Gemini 3.5 FlashLeader
AA Agentic Index50.7Not measuredOnly Claude Fable 5 measured
Design Arena: agents building web apps12611202Claude Fable 5
Design Arena: agents building full-stack apps12801197Claude Fable 5
Design Arena: agents building mobile apps12641175Claude Fable 5
Design Arena: agents building Android apps12891190Claude Fable 5
Design Arena: agents building Godot games12921098Claude Fable 5
Design Arena: agents building games12851180Claude Fable 5
Design Arena: HTML slides12771142Claude Fable 5
Design Arena: PowerPoint slides12951178Claude Fable 5
LiveBench research86.9%Not measuredOnly Claude Fable 5 measured
LiveBench browser92.0%Not measuredOnly Claude Fable 5 measured
LiveBench long agentic53.2%Not measuredOnly Claude Fable 5 measured
Finance Agent (Vals AI)56.3%57.9%Gemini 3.5 Flash
Tax Agent Bench (Vals AI)38.3%21.6%Claude Fable 5
Legal Research Bench (Vals AI)49.5%30.8%Claude Fable 5
Excel Modeling Benchmark (Vals AI)73.7%63.5%Claude Fable 5
Terminal-Bench-Science (Vals AI)15.7%5.7%Claude Fable 5
τ²-Bench Telecom98.5%95.6%Claude Fable 5
APEX-Agents63.6%27.5%Claude Fable 5
Remote Labor Index16.1%Not measuredOnly Claude Fable 5 measured
PostTrainBench41.8%Not measuredOnly Claude Fable 5 measured
Vending-Bench 2$5,680$5,396Claude Fable 5
LMArena Search1229Not measuredOnly Claude Fable 5 measured
Neither model has a result on the other 16 boards here
ReasoningLike-for-likePublic boards, shown as published, kept out of the index151
Reasoning benchmarks for Claude Fable 5 and Gemini 3.5 Flash
BenchmarkClaude Fable 5Gemini 3.5 FlashLeader
GPQA Diamond93.2%92.7%Claude Fable 5
LiveBench reasoning89.7%Not measuredOnly Claude Fable 5 measured
MMMU Pro (Vals AI)89.3%88.3%Claude Fable 5
GPQA Diamond (Artificial Analysis run)92.6%92.2%Claude Fable 5
Humanity's Last Exam (Artificial Analysis run)55.5%42.7%Claude Fable 5
GPQA Diamond (Epoch AI run)85.9%92.8%Gemini 3.5 Flash
ARC-AGI98.5%92.5%Claude Fable 5
ARC-AGI-289.2%72.1%Claude Fable 5
SimpleBench81.9%76.7%Claude Fable 5
Chess puzzles47.0%45.0%Claude Fable 5
Mystery game puzzles52.0%32.0%Claude Fable 5
EBR-bench39.5%4.8%Claude Fable 5
LMArena Text: hard prompts15071488Claude Fable 5
LMArena Text: expert15341495Claude Fable 5
LMArena Text: hard prompts in English15091483Claude Fable 5
LMArena Vision: diagrams13571323Claude Fable 5
LMArena Vision: homework13611330Claude Fable 5
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 and Gemini 3.5 Flash
BenchmarkClaude Fable 5Gemini 3.5 FlashLeader
OTIS Mock AIME100.0%95.6%Claude Fable 5
FrontierMath, tiers 1 to 387.0%62.8%Claude Fable 5
FrontierMath, tier 490.2%26.8%Claude Fable 5
ProofBench95.0%31.0%Claude Fable 5
LMArena Text: math15161504Claude Fable 5
LMArena Text: mathematical work15151495Claude Fable 5
Neither model has a result on the other 7 boards here
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index101
Knowledge benchmarks for Claude Fable 5 and Gemini 3.5 Flash
BenchmarkClaude Fable 5Gemini 3.5 FlashLeader
MMLU Pro91.5%89.5%Claude Fable 5
LegalBench (Vals AI)88.6%83.6%Claude Fable 5
CorpFin (Vals AI)71.8%64.7%Claude Fable 5
TaxEval (Vals AI)76.9%74.4%Claude Fable 5
MortgageTax (Vals AI)68.9%68.1%Claude Fable 5
MedCode (Vals AI)56.1%55.8%Claude Fable 5
SimpleQA Verified70.7%66.2%Claude Fable 5
LMArena Text: science15061495Claude Fable 5
LMArena Text: medicine and healthcare14801483Gemini 3.5 Flash
LMArena Text: legal and government14981488Claude Fable 5
LMArena Text: business and finance14801467Claude Fable 5
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 and Gemini 3.5 Flash
BenchmarkClaude Fable 5Gemini 3.5 FlashLeader
Design Arena: websites12961268Claude Fable 5
Design Arena: UI components13181272Claude Fable 5
Design Arena: game dev13361263Claude Fable 5
Design Arena: data viz13041236Claude Fable 5
Design Arena: 3D13191244Claude Fable 5
Design Arena: all code categories13101266Claude Fable 5
Design Arena: SVG13021254Claude Fable 5
Design Arena: ASCII art13281253Claude Fable 5
LiveBench design84.7%Not measuredOnly Claude Fable 5 measured
GeneralLike-for-likePublic boards, shown as published, kept out of the index294
General benchmarks for Claude Fable 5 and Gemini 3.5 Flash
BenchmarkClaude Fable 5Gemini 3.5 FlashLeader
LiveBench data analysis80.5%Not measuredOnly Claude Fable 5 measured
Public Benefits Bench (Vals AI)70.4%59.5%Claude Fable 5
SAGE (Vals AI)51.9%49.9%Claude Fable 5
MedScribe (Vals AI)88.5%76.6%Claude Fable 5
Vals Multimodal Index74.2%62.9%Claude Fable 5
IFBench63.5%76.3%Gemini 3.5 Flash
Long context reasoning (AA-LCR)82.3%74.3%Claude Fable 5
DTBench98.4%94.7%Claude Fable 5
LMCA61.2%47.1%Claude Fable 5
Surface Evolver Bench95.0%58.1%Claude Fable 5
Furniture assembly35.8%Not measuredOnly Claude Fable 5 measured
LMArena Text14911482Claude Fable 5
LMArena Text: instruction following15021467Claude Fable 5
LMArena Text: creative writing14941470Claude Fable 5
LMArena Vision13251308Claude Fable 5
LMArena Text: English14981481Claude Fable 5
LMArena Text: non-English14821475Claude Fable 5
LMArena Text: Chinese15431527Claude Fable 5
LMArena Text: German14861494Gemini 3.5 Flash
LMArena Text: Japanese15041486Claude Fable 5
LMArena Text: Korean14871448Claude Fable 5
LMArena Text: French15051490Claude Fable 5
LMArena Text: Spanish14981480Claude Fable 5
LMArena Text: Russian15031493Claude Fable 5
LMArena Text: Polish14941516Gemini 3.5 Flash
LMArena Text: multi-turn15041481Claude Fable 5
LMArena Text: longer queries15101483Claude Fable 5
LMArena Text: writing and language15011478Claude Fable 5
LMArena Text: entertainment and media14821459Claude Fable 5
LMArena Vision: English13231305Claude Fable 5
LMArena Vision: Chinese13731377Gemini 3.5 Flash
LMArena Vision: reading text13371317Claude Fable 5
LMArena Vision: humor13411321Claude Fable 5
LMArena Vision: creative writing13381301Claude Fable 5
LMArena Document14961463Claude Fable 5
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 and Gemini 3.5 Flash
BenchmarkClaude Fable 5Gemini 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$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$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$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 and Gemini 3.5 Flash
SpecificationAnthropic Claude Fable 5Google Gemini 3.5 Flash
MakerAnthropicGoogle
WeightsNo public weights listedNo public weights listed
ReleasedJune 9, 2026May 19, 2026
Context window1M1.05M
Input $/Mtok$10.00$1.50
Output $/Mtok$50.00$9.00
Coding index82.142.8
Independent measurements behind it21
Cost per solved task$2.16$1.21
SourceOpenRouter listingOpenRouter listing

Questions

Is Claude Fable 5 better than Gemini 3.5 Flash for coding?

Pick Claude Fable 5 for coding: it scores 82.1 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 a solved task costs $1.21 against $2.16.

Which is cheaper, Claude Fable 5 or Gemini 3.5 Flash?

Claude Fable 5 costs $10.00 per million input tokens and $50.00 per million output tokens; Gemini 3.5 Flash costs $1.50 and $9.00. Per solved SWE-bench Verified task, Claude Fable 5 costs $2.16 and Gemini 3.5 Flash $1.21.

Which has the bigger context window, Claude Fable 5 or Gemini 3.5 Flash?

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

How many benchmarks is the Claude Fable 5 vs Gemini 3.5 Flash comparison based on?

109 benchmarks have a result for both models as of October 21, 2026. Claude Fable 5'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.

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