Noometry

Model comparison

Claude Fable 5.1 vs Gemini 2.5 Flash

Claude Fable 5.1 is the stronger model overall, scoring 68.5 to 39.0 on the Noometry Index. Gemini 2.5 Flash costs 24× less per token, which makes it the better buy when Claude Fable 5.1's lead doesn't matter for your workload.

Last verified . 29 shared benchmarks.

Claude Fable 5.1 Anthropic

68.5

Rank #2 Confirmed

Gemini 2.5 Flash Google

39.0

Rank #162 Confirmed

Summary

  • They share 29 benchmarks with published results for both. Claude Fable 5.1 scores higher in 9 categories and Gemini 2.5 Flash in 1 category; 9 gaps are clear of the uncertainty.
  • The widest gap is in reasoning, where Claude Fable 5.1 leads 76.7 to 18.2.
  • The biggest single-benchmark swing is ARC-AGI-2: 90% for Claude Fable 5.1 and 2.5% for Gemini 2.5 Flash.
  • Gemini 2.5 Flash is cheaper at $0.30 / $2.50 per million input/output tokens, against $10 / $50 for Claude Fable 5.1.
  • Gemini 2.5 Flash accepts more context: 1.05M tokens versus 1M.

Side by side

Claude Fable 5.1Gemini 2.5 Flash
ProviderAnthropicGoogle
Noometry Index68.539.0
Released2026-09-012025-04-17
WeightsProprietaryProprietary
Context window1M1.05M
Max output128K66K
Input $ / M tokens$10$0.30
Output $ / M tokens$50$2.50
Results tracked5054

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Category by category

Coding Claude Fable 5.1 leads

Claude Fable 5.1: 70.5 (#2), Gemini 2.5 Flash: 35.5 (#210)

BenchmarkClaude Fable 5.1Gemini 2.5 Flash
WeirdML92.9%41.9%
LMArena Coding15231424
ALE-Bench2,143661.88
FrontierCode50.9%—
SWE-bench Verified (bash only)—28.7%
Aider Polyglot—55.1%
CursorBench51.8%—
LMArena WebDev1753—
FrontierSWE56.3%—
SciCode63.1%—
MirrorCode73.3%—

Agentic & Tool Use Claude Fable 5.1 leads

Claude Fable 5.1: 50.8 (#5), Gemini 2.5 Flash: 30.6 (#67)

BenchmarkClaude Fable 5.1Gemini 2.5 Flash
Vending-Bench 25,422548.84
Terminal-Bench—17.1%
APEX-Agents68.6%—
Berkeley Function Calling Leaderboard—56.2%
Remote Labor Index17.9%—
TheAgentCompany—41.1%
BALROG—33.5%
GDP.pdf29.6%—

Reasoning Claude Fable 5.1 leads

Claude Fable 5.1: 76.7 (#5), Gemini 2.5 Flash: 18.2 (#271)

BenchmarkClaude Fable 5.1Gemini 2.5 Flash
ARC-AGI-290%2.5%
ARC-AGI-197.5%33.3%
CritPt31.1%1.1%
LMArena Hard Prompts15261422
DTBench97.6%76.5%
LMCA65.5%27.5%
Epoch Capabilities Index165143.04
SimpleBench—41.2%
Kagi LLM Benchmark—56.8%
NYT Connections (extended)90%—
Chess Puzzles47%—
EnigmaEval—2.7%
EBR-Bench57.1%—
Mystery Game Puzzles58%—
ForecastBench—60.6

Math Claude Fable 5.1 leads

Claude Fable 5.1: 89.5 (#3), Gemini 2.5 Flash: 38.1 (#87)

BenchmarkClaude Fable 5.1Gemini 2.5 Flash
OTIS Mock AIME 2024-2025100%73.1%
LMArena Math15191415
FrontierMath (Tiers 1-3)90.2%—
FrontierMath Tier 487.8%—
ProofBench100%—
Omni-MATH—38.5%
FrontierMath (Feb 2025 set)—4.8%
FrontierMath Erdős0%—
FrontierMath Tier 4 (v1)—4.2%

Knowledge Claude Fable 5.1 leads

Claude Fable 5.1: 69.3 (#5), Gemini 2.5 Flash: 36.1 (#162)

BenchmarkClaude Fable 5.1Gemini 2.5 Flash
Humanity's Last Exam46.5%12.1%
LMArena Expert15281426
SimpleQA Verified70.8%—
MMLU-Pro—63.9%
Confabulations—16.8%
Vectara Hallucination Rate—7.8%
GPQA (HELM)—39%

Multimodal Claude Fable 5.1 leads

Claude Fable 5.1: 54.1 (#4), Gemini 2.5 Flash: 41.2 (#31)

BenchmarkClaude Fable 5.1Gemini 2.5 Flash
LMArena Vision13191254
GeoBench—76%
VPCT—46.2%
Blueprint-Bench 241.9%—
Furniture Assembly70%—
LMArena Document1513—
SpatialViz-Bench—36.9%

Multilingual Claude Fable 5.1 leads

Claude Fable 5.1: 59.5 (#2), Gemini 2.5 Flash: 52.5 (#83)

BenchmarkClaude Fable 5.1Gemini 2.5 Flash
LMArena Non-English15091410
LMArena Chinese15891450
LMArena French15321433
LMArena German14951419
LMArena Japanese15651403
LMArena Russian15251415
LMArena Spanish15031421
LMArena Korean—1385

Instruction Following Claude Fable 5.1 leads

Claude Fable 5.1: 79.3 (#6), Gemini 2.5 Flash: 75.9 (#50)

BenchmarkClaude Fable 5.1Gemini 2.5 Flash
LMArena Instruction Following15151405
IFEval—89.8%

Long Context Too close to call

Claude Fable 5.1: 46.8 (#19), Gemini 2.5 Flash: 47.5 (#16)

BenchmarkClaude Fable 5.1Gemini 2.5 Flash
LMArena Longer Query15241419
Fiction.LiveBench—77.8%

Writing & Preference Claude Fable 5.1 leads

Claude Fable 5.1: 79.3 (#1), Gemini 2.5 Flash: 54.0 (#153)

BenchmarkClaude Fable 5.1Gemini 2.5 Flash
LMArena Text15111417
LMArena Creative Writing15071400
EQ-Bench Creative Writing21621137
LMArena Multi-Turn14921408
Short-Story Creative Writing—76.5%
WildBench—81.7%

Frequently asked questions

Is Claude Fable 5.1 better than Gemini 2.5 Flash?

Claude Fable 5.1 is the stronger model overall, scoring 68.5 to 39.0 on the Noometry Index. Gemini 2.5 Flash costs 24× less per token, which makes it the better buy when Claude Fable 5.1's lead doesn't matter for your workload.

Which is cheaper, Claude Fable 5.1 or Gemini 2.5 Flash?

Gemini 2.5 Flash is cheaper. It lists at $0.30 per million input tokens and $2.50 per million output tokens; Claude Fable 5.1 lists at $10 and $50.

Is Claude Fable 5.1 or Gemini 2.5 Flash better for coding?

Claude Fable 5.1 scores higher on coding benchmarks: 70.5 versus 35.5 in the Noometry coding category.

Which has the bigger context window?

Gemini 2.5 Flash does, with 1.05M tokens against 1M.

How many benchmarks do Claude Fable 5.1 and Gemini 2.5 Flash share?

29 benchmarks have published results for both models. Claude Fable 5.1 has 50 scored results on Noometry and Gemini 2.5 Flash has 54.

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