Noometry

Model comparison

Claude Fable 5.1 vs Claude Opus 4.6

Claude Fable 5.1 is the stronger model overall, scoring 69.0 to 58.2 on the Noometry Index. Claude Opus 4.6 costs 2.0× less per token, which makes it the better buy when Claude Fable 5.1's lead doesn't matter for your workload.

Last verified . 44 shared benchmarks.

Claude Fable 5.1 Anthropic

69.0

Rank #2 Confirmed

Claude Opus 4.6 Anthropic

58.2

Rank #20 Confirmed

Summary

  • They share 44 benchmarks with published results for both. Claude Fable 5.1 scores higher in 7 categories and Claude Opus 4.6 in 3 categories; 8 gaps are clear of the uncertainty.
  • The widest gap is in math, where Claude Fable 5.1 leads 89.6 to 63.0.
  • The biggest single-benchmark swing is FrontierMath Tier 4: 87.8% for Claude Fable 5.1 and 26.8% for Claude Opus 4.6.
  • Claude Opus 4.6 is cheaper at $5 / $25 per million input/output tokens, against $10 / $50 for Claude Fable 5.1.

Side by side

Claude Fable 5.1Claude Opus 4.6
ProviderAnthropicAnthropic
Noometry Index69.058.2
Released2026-09-012026-02-04
WeightsProprietaryProprietary
Context window1M1M
Max output128K128K
Input $ / M tokens$10$5
Output $ / M tokens$50$25
Results tracked5268

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Category by category

Coding Claude Fable 5.1 leads

Claude Fable 5.1: 74.7 (#1), Claude Opus 4.6: 57.2 (#20)

BenchmarkClaude Fable 5.1Claude Opus 4.6
FrontierCode50.9%26.6%
LMArena WebDev17441547
GSO88.2%41.2%
WeirdML92.9%78%
LMArena Coding15281536
ALE-Bench2,143996.5
SWE-bench Verified—78.7%
SWE-bench Verified (bash only)—75.6%
CursorBench51.8%—
SWE-bench Multilingual—72%
FrontierSWE56.3%—
SciCode63.1%—
MirrorCode73.3%—
AlgoTune—1.47

Agentic & Tool Use Too close to call

Claude Fable 5.1: 50.7 (#5), Claude Opus 4.6: 51.1 (#4)

BenchmarkClaude Fable 5.1Claude Opus 4.6
APEX-Agents68.6%46.3%
Remote Labor Index17.9%4.2%
Vending-Bench 25,4228,018
Terminal-Bench—79.8%
τ²-bench Banking—27.3%
Cybench—93%
DeepResearch Bench—55.3%
GBAEval—44.1%
GDP.pdf29.6%—
LMArena Search—1253
METR Time Horizons—78.9%

Reasoning Claude Fable 5.1 leads

Claude Fable 5.1: 76.7 (#7), Claude Opus 4.6: 57.8 (#23)

BenchmarkClaude Fable 5.1Claude Opus 4.6
ARC-AGI-290%69.2%
NYT Connections (extended)90%92.1%
ARC-AGI-197.5%94%
Chess Puzzles47%17%
EBR-Bench57.1%12.7%
LMArena Hard Prompts15261527
Mystery Game Puzzles58%25%
DTBench97.6%91.2%
LMCA65.5%55.8%
Epoch Capabilities Index164.7155.24
SimpleBench—67.6%
Kagi LLM Benchmark—83.6%
CritPt31.1%—
EnigmaEval—7.6%
Thematic Generalization—80.6%
ForecastBench—60

Math Claude Fable 5.1 leads

Claude Fable 5.1: 89.6 (#4), Claude Opus 4.6: 63.0 (#31)

BenchmarkClaude Fable 5.1Claude Opus 4.6
FrontierMath (Tiers 1-3)90.2%66%
FrontierMath Tier 487.8%26.8%
OTIS Mock AIME 2024-2025100%94.4%
ProofBench100%50%
LMArena Math15251519
MathArena Final-Answer Competitions—78.5%
FrontierMath (Feb 2025 set)—40.7%
FrontierMath Erdős0%—
FrontierMath Tier 4 (v1)—22.9%

Knowledge Claude Fable 5.1 leads

Claude Fable 5.1: 69.6 (#6), Claude Opus 4.6: 61.9 (#26)

BenchmarkClaude Fable 5.1Claude Opus 4.6
Humanity's Last Exam46.5%34.4%
SimpleQA Verified70.8%47%
LMArena Expert15351546
GPQA Diamond—90.5%
Vectara Hallucination Rate—12.2%

Multimodal Claude Fable 5.1 leads

Claude Fable 5.1: 53.9 (#4), Claude Opus 4.6: 37.3 (#74)

BenchmarkClaude Fable 5.1Claude Opus 4.6
LMArena Vision13181316
Furniture Assembly70%28.3%
LMArena Document15131507
Blueprint-Bench 241.9%—

Multilingual Claude Fable 5.1 leads

Claude Fable 5.1: 59.1 (#3), Claude Opus 4.6: 57.9 (#6)

BenchmarkClaude Fable 5.1Claude Opus 4.6
LMArena Non-English15071489
LMArena Chinese15861551
LMArena French15251513
LMArena German15001502
LMArena Japanese15431484
LMArena Korean15341464
LMArena Russian15211497
LMArena Spanish15161510

Instruction Following Too close to call

Claude Fable 5.1: 79.2 (#6), Claude Opus 4.6: 79.5 (#4)

BenchmarkClaude Fable 5.1Claude Opus 4.6
LMArena Instruction Following15171523

Long Context Claude Opus 4.6 leads

Claude Fable 5.1: 46.7 (#20), Claude Opus 4.6: 48.1 (#13)

BenchmarkClaude Fable 5.1Claude Opus 4.6
LMArena Longer Query15221520
CL-bench—20.7%
CL-bench Life—17%

Writing & Preference Claude Fable 5.1 leads

Claude Fable 5.1: 79.2 (#2), Claude Opus 4.6: 73.5 (#10)

BenchmarkClaude Fable 5.1Claude Opus 4.6
LMArena Text15101503
LMArena Creative Writing15071505
EQ-Bench Creative Writing21621809
LMArena Multi-Turn14921513
EQ-Bench 4—1223

Frequently asked questions

Is Claude Fable 5.1 better than Claude Opus 4.6?

Claude Fable 5.1 is the stronger model overall, scoring 69.0 to 58.2 on the Noometry Index. Claude Opus 4.6 costs 2.0× 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 Claude Opus 4.6?

Claude Opus 4.6 is cheaper. It lists at $5 per million input tokens and $25 per million output tokens; Claude Fable 5.1 lists at $10 and $50.

Is Claude Fable 5.1 or Claude Opus 4.6 better for coding?

Claude Fable 5.1 scores higher on coding benchmarks: 74.7 versus 57.2 in the Noometry coding category.

Which has the bigger context window?

Both accept 1M tokens.

How many benchmarks do Claude Fable 5.1 and Claude Opus 4.6 share?

44 benchmarks have published results for both models. Claude Fable 5.1 has 52 scored results on Noometry and Claude Opus 4.6 has 68.

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