Noometry

Model comparison

Claude Fable 5.1 vs GPT-5

Claude Fable 5.1 is the stronger model overall, scoring 69.0 to 50.9 on the Noometry Index. GPT-5 costs 5.8× less per token, which makes it the better buy when Claude Fable 5.1's lead doesn't matter for your workload.

Last verified . 40 shared benchmarks.

Claude Fable 5.1 Anthropic

69.0

Rank #2 Confirmed

GPT-5 OpenAI

50.9

Rank #45 Confirmed

Summary

  • They share 40 benchmarks with published results for both. Claude Fable 5.1 scores higher in 9 categories and GPT-5 in 1 category; 10 gaps are clear of the uncertainty.
  • The widest gap is in reasoning, where Claude Fable 5.1 leads 76.7 to 38.3.
  • The biggest single-benchmark swing is ProofBench: 100% for Claude Fable 5.1 and 18% for GPT-5.
  • GPT-5 is cheaper at $1.25 / $10 per million input/output tokens, against $10 / $50 for Claude Fable 5.1.
  • Claude Fable 5.1 accepts more context: 1M tokens versus 400K.

Side by side

Claude Fable 5.1GPT-5
ProviderAnthropicOpenAI
Noometry Index69.050.9
Released2026-09-012025-08-07
WeightsProprietaryProprietary
Context window1M400K
Max output128K128K
Input $ / M tokens$10$1.25
Output $ / M tokens$50$10
Results tracked5269

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Category by category

Coding Claude Fable 5.1 leads

Claude Fable 5.1: 74.7 (#1), GPT-5: 50.3 (#47)

BenchmarkClaude Fable 5.1GPT-5
LMArena WebDev17441418
SciCode63.1%42.9%
GSO88.2%6.9%
WeirdML92.9%60.7%
LMArena Coding15281436
ALE-Bench2,1431,162
SWE-bench Verified—73.6%
FrontierCode50.9%—
SWE-bench Verified (bash only)—65%
Aider Polyglot—88%
CursorBench51.8%—
FrontierSWE56.3%—
MirrorCode73.3%—
AlgoTune—1.67

Agentic & Tool Use Claude Fable 5.1 leads

Claude Fable 5.1: 50.7 (#5), GPT-5: 33.1 (#56)

BenchmarkClaude Fable 5.1GPT-5
Remote Labor Index17.9%1.7%
Terminal-Bench—49.6%
APEX-Agents68.6%—
GDPval—34.8%
DeepResearch Bench—49.6%
BALROG—32.8%
GDP.pdf29.6%—
LMArena Search—1133
METR Time Horizons—69.6%
Vending-Bench 25,422—

Reasoning Claude Fable 5.1 leads

Claude Fable 5.1: 76.7 (#7), GPT-5: 38.3 (#64)

BenchmarkClaude Fable 5.1GPT-5
ARC-AGI-290%9.9%
ARC-AGI-197.5%65.7%
CritPt31.1%12.6%
Chess Puzzles47%37%
EBR-Bench57.1%12.7%
LMArena Hard Prompts15261416
Mystery Game Puzzles58%23%
DTBench97.6%90.7%
LMCA65.5%40%
Epoch Capabilities Index164.7150
SimpleBench—56.7%
Kagi LLM Benchmark—72.7%
NYT Connections (extended)90%—
EnigmaEval—10.5%
ForecastBench—61.4

Math Claude Fable 5.1 leads

Claude Fable 5.1: 89.6 (#4), GPT-5: 55.0 (#44)

BenchmarkClaude Fable 5.1GPT-5
FrontierMath (Tiers 1-3)90.2%55.4%
FrontierMath Tier 487.8%22%
OTIS Mock AIME 2024-2025100%91.4%
ProofBench100%18%
LMArena Math15251407
Omni-MATH—64.7%
MATH Level 5—98.1%
FrontierMath (Feb 2025 set)—32.4%
FrontierMath Erdős0%—
FrontierMath Tier 4 (v1)—12.5%

Knowledge Claude Fable 5.1 leads

Claude Fable 5.1: 69.6 (#6), GPT-5: 56.6 (#43)

BenchmarkClaude Fable 5.1GPT-5
Humanity's Last Exam46.5%25.3%
SimpleQA Verified70.8%50.1%
LMArena Expert15351419
GPQA Diamond—86.2%
MMLU-Pro—86.3%
Confabulations—10.3%
Vectara Hallucination Rate—14.7%
GPQA (HELM)—79.2%

Multimodal Claude Fable 5.1 leads

Claude Fable 5.1: 53.9 (#4), GPT-5: 46.8 (#13)

BenchmarkClaude Fable 5.1GPT-5
LMArena Vision13181232
GeoBench—81%
VPCT—66%
Blueprint-Bench 241.9%—
Furniture Assembly70%—
LMArena Document1513—

Multilingual Claude Fable 5.1 leads

Claude Fable 5.1: 59.1 (#3), GPT-5: 51.4 (#110)

BenchmarkClaude Fable 5.1GPT-5
LMArena Non-English15071397
LMArena Chinese15861422
LMArena French15251410
LMArena German15001416
LMArena Japanese15431409
LMArena Korean15341360
LMArena Russian15211406
LMArena Spanish15161399

Instruction Following Claude Fable 5.1 leads

Claude Fable 5.1: 79.2 (#6), GPT-5: 73.8 (#113)

BenchmarkClaude Fable 5.1GPT-5
LMArena Instruction Following15171388
IFEval—87.5%

Long Context GPT-5 leads

Claude Fable 5.1: 46.7 (#20), GPT-5: 69.5 (#2)

BenchmarkClaude Fable 5.1GPT-5
LMArena Longer Query15221399
Fiction.LiveBench—97.2%

Writing & Preference Claude Fable 5.1 leads

Claude Fable 5.1: 79.2 (#2), GPT-5: 63.4 (#65)

BenchmarkClaude Fable 5.1GPT-5
LMArena Text15101406
LMArena Creative Writing15071365
EQ-Bench Creative Writing21621627
LMArena Multi-Turn14921426
Short-Story Creative Writing—86%
WildBench—85.7%

Frequently asked questions

Is Claude Fable 5.1 better than GPT-5?

Claude Fable 5.1 is the stronger model overall, scoring 69.0 to 50.9 on the Noometry Index. GPT-5 costs 5.8× 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 GPT-5?

GPT-5 is cheaper. It lists at $1.25 per million input tokens and $10 per million output tokens; Claude Fable 5.1 lists at $10 and $50.

Is Claude Fable 5.1 or GPT-5 better for coding?

Claude Fable 5.1 scores higher on coding benchmarks: 74.7 versus 50.3 in the Noometry coding category.

Which has the bigger context window?

Claude Fable 5.1 does, with 1M tokens against 400K.

How many benchmarks do Claude Fable 5.1 and GPT-5 share?

40 benchmarks have published results for both models. Claude Fable 5.1 has 52 scored results on Noometry and GPT-5 has 69.

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