Noometry

Model comparison

Claude Fable 5 vs Grok 4.20 (Non-Reasoning)

Claude Fable 5 is the stronger model overall, scoring 66.8 to 48.6 on the Noometry Index. Grok 4.20 (Non-Reasoning) costs 13× less per token, which makes it the better buy when Claude Fable 5's lead doesn't matter for your workload.

Last verified . 41 shared benchmarks.

Claude Fable 5 Anthropic

66.8

Rank #5 Confirmed

Grok 4.20 (Non-Reasoning) xAI

48.6

Rank #54 Confirmed

Summary

  • They share 41 benchmarks with published results for both. Claude Fable 5 scores higher in 10 categories and Grok 4.20 (Non-Reasoning) in 0 categories; 9 gaps are clear of the uncertainty.
  • The widest gap is in math, where Claude Fable 5 leads 88.5 to 48.2.
  • The biggest single-benchmark swing is ProofBench: 95% for Claude Fable 5 and 14% for Grok 4.20 (Non-Reasoning).
  • Grok 4.20 (Non-Reasoning) is cheaper at $1.25 / $2.50 per million input/output tokens, against $10 / $50 for Claude Fable 5.

Side by side

Claude Fable 5Grok 4.20 (Non-Reasoning)
ProviderAnthropicxAI
Noometry Index66.848.6
Released2026-06-072026-02-17
WeightsProprietaryProprietary
Context window1M1M
Max output128K30K
Input $ / M tokens$10$1.25
Output $ / M tokens$50$2.50
Results tracked6246

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Category by category

Coding Claude Fable 5 leads

Claude Fable 5: 70.6 (#4), Grok 4.20 (Non-Reasoning): 42.1 (#112)

BenchmarkClaude Fable 5Grok 4.20 (Non-Reasoning)
LMArena WebDev16251375
WeirdML91.9%52.3%
LMArena Coding15191459
ALE-Bench2,0411,150
DeepSWE69.9%—
FrontierCode53.5%—
FrontierSWE47%—
SciCode61%—
GSO78.4%—
MirrorCode63.9%—

Agentic & Tool Use Claude Fable 5 leads

Claude Fable 5: 54.0 (#2), Grok 4.20 (Non-Reasoning): 34.4 (#46)

BenchmarkClaude Fable 5Grok 4.20 (Non-Reasoning)
τ²-bench Banking39.7%18%
LMArena Search12301189
Vending-Bench 25,6804,663
Terminal-Bench—57.3%
APEX-Agents63.6%—
Remote Labor Index16.1%—
PostTrainBench41.8%—
GBAEval74.5%—
GDP.pdf30%—

Reasoning Claude Fable 5 leads

Claude Fable 5: 76.8 (#6), Grok 4.20 (Non-Reasoning): 52.3 (#32)

BenchmarkClaude Fable 5Grok 4.20 (Non-Reasoning)
ARC-AGI-289.2%65.1%
Kagi LLM Benchmark91.4%75%
NYT Connections (extended)92.7%85.4%
ARC-AGI-198.5%89.5%
Chess Puzzles41%24%
LMArena Hard Prompts15081451
DTBench98.4%90.1%
LMCA61.1%38.7%
Epoch Capabilities Index162.06151.98
SimpleBench81.9%—
CritPt28.6%—
EnigmaEval39.3%—
Thematic Generalization—63.8%
EBR-Bench39.5%—
Mystery Game Puzzles52%—
Surface Evolver Bench95%—
Bench to the Future 30.13—
ForecastBench—61.4

Math Claude Fable 5 leads

Claude Fable 5: 88.5 (#5), Grok 4.20 (Non-Reasoning): 48.2 (#65)

BenchmarkClaude Fable 5Grok 4.20 (Non-Reasoning)
FrontierMath (Tiers 1-3)87%44.9%
FrontierMath Tier 490.2%17.1%
OTIS Mock AIME 2024-2025100%92.2%
ProofBench95%14%
LMArena Math15191455
FrontierMath Erdős0%—

Knowledge Claude Fable 5 leads

Claude Fable 5: 62.2 (#25), Grok 4.20 (Non-Reasoning): 52.8 (#60)

BenchmarkClaude Fable 5Grok 4.20 (Non-Reasoning)
GPQA Diamond85.9%89.3%
SimpleQA Verified70.7%30.2%
LMArena Expert15341439

Multimodal Claude Fable 5 leads

Claude Fable 5: 45.3 (#17), Grok 4.20 (Non-Reasoning): 33.3 (#98)

BenchmarkClaude Fable 5Grok 4.20 (Non-Reasoning)
LMArena Vision13241263
Blueprint-Bench 238.6%0%
LMArena Document14961416
Furniture Assembly35.8%—

Multilingual Claude Fable 5 leads

Claude Fable 5: 57.3 (#9), Grok 4.20 (Non-Reasoning): 54.5 (#40)

BenchmarkClaude Fable 5Grok 4.20 (Non-Reasoning)
LMArena Non-English14811441
LMArena Chinese15431481
LMArena French15051476
LMArena German14861465
LMArena Japanese15061449
LMArena Korean14881417
LMArena Russian15041458
LMArena Spanish14981443

Instruction Following Claude Fable 5 leads

Claude Fable 5: 78.6 (#8), Grok 4.20 (Non-Reasoning): 74.8 (#83)

BenchmarkClaude Fable 5Grok 4.20 (Non-Reasoning)
LMArena Instruction Following15021420

Long Context Too close to call

Claude Fable 5: 46.3 (#23), Grok 4.20 (Non-Reasoning): 45.5 (#34)

BenchmarkClaude Fable 5Grok 4.20 (Non-Reasoning)
LMArena Longer Query15091437
CL-bench—22.2%
CL-bench Life—11.9%

Writing & Preference Claude Fable 5 leads

Claude Fable 5: 75.9 (#5), Grok 4.20 (Non-Reasoning): 65.7 (#44)

BenchmarkClaude Fable 5Grok 4.20 (Non-Reasoning)
LMArena Text14911451
LMArena Creative Writing14941438
EQ-Bench Creative Writing19431574
LMArena Multi-Turn15041456
EQ-Bench 41340—

Frequently asked questions

Is Claude Fable 5 better than Grok 4.20 (Non-Reasoning)?

Claude Fable 5 is the stronger model overall, scoring 66.8 to 48.6 on the Noometry Index. Grok 4.20 (Non-Reasoning) costs 13× less per token, which makes it the better buy when Claude Fable 5's lead doesn't matter for your workload.

Which is cheaper, Claude Fable 5 or Grok 4.20 (Non-Reasoning)?

Grok 4.20 (Non-Reasoning) is cheaper. It lists at $1.25 per million input tokens and $2.50 per million output tokens; Claude Fable 5 lists at $10 and $50.

Is Claude Fable 5 or Grok 4.20 (Non-Reasoning) better for coding?

Claude Fable 5 scores higher on coding benchmarks: 70.6 versus 42.1 in the Noometry coding category.

Which has the bigger context window?

Both accept 1M tokens.

How many benchmarks do Claude Fable 5 and Grok 4.20 (Non-Reasoning) share?

41 benchmarks have published results for both models. Claude Fable 5 has 62 scored results on Noometry and Grok 4.20 (Non-Reasoning) has 46.

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