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Claude Fable 5.1 vs Grok 4.20

Full profiles: Claude Fable 5.1 (Anthropic) and Grok 4.20 (SpaceXAI): every benchmark, price and rank.

Updated · Data from 12 sources

As of 6 Nov 2026, Claude Fable 5.1 is ahead of Grok 4.20 on quality (67.2 vs 58.4 on the BenchLeader Index), but Grok 4.20 is 13× cheaper at $1.56 vs $20.00 per 1M tokens blended. Claude Fable 5.1 leads in every category we measure both in. Grok 4.20 streams ~1.5× faster.

Key facts (as of 6 Nov 2026)

  • Claude Fable 5.1 scores 67.2 on the BenchLeader Index and Grok 4.20 scores 58.4 (BenchLeader, 6 Nov 2026).
  • Claude Fable 5.1 costs $20.00 per 1M tokens blended (list price, 6 Nov 2026).
  • Grok 4.20 costs $1.56 per 1M tokens blended (list price, 6 Nov 2026).
  • Grok 4.20 streams ~1.5× faster than Claude Fable 5.1 (Artificial Analysis, 7-day median, 6 Nov 2026).
  • Of the 23 benchmarks both models have, Claude Fable 5.1 leads 23 (BenchLeader, 6 Nov 2026).
  • On Arena WebDev, Claude Fable 5.1 is rated 1746 and Grok 4.20 1376 (LMArena, as published by 6 Nov 2026).
Claude Fable 5.1 benchmarks max Anthropic Grok 4.20 benchmarks thinking SpaceXAIAdd a third model

Which to pick for…

The pick's numbers come first. Category scores on the BenchLeader scale (50 is the average model, 15 points one standard deviation). High confidence means a lead of half a standard deviation or more; under one point is called either.

Use casePickWhyConfidence
CodingClaude Fable 5.171 vs 54 category score; Arena WebDev 1746 vs 1376High
Agents & tool useClaude Fable 5.160 vs 51 category scoreHigh
MathsClaude Fable 5.173 vs 54 category score; FrontierMath Tiers 1–3 90.2% vs 44.9%High
ReasoningClaude Fable 5.171 vs 61 category score; ARC-AGI-2 90.0% vs 65.1%High
KnowledgeClaude Fable 5.174 vs 53 category score; SimpleQA Verified 70.8% vs 30.2%High
Long documentsClaude Fable 5.168 vs 59 category score; AA-LCR v1.1 85.3% vs 69.0%High
Images and other mediaClaude Fable 5.167 vs 58 category score; Arena Vision 1320 vs 1262High
Chat quality (human preference)Claude Fable 5.170 vs 66 on Arena votesMedium
Lowest costGrok 4.20$1.56 vs $20.00 per 1M blended; agentic coding session $0.085 vs $0.800–
Fastest first answerGrok 4.2019.9 s (Grok 4.20 (thinking)) vs 183.7 s (Claude Fable 5.1 (max)) to the first answer token–
High volume on a budgetNeither flagshipA smaller model is usually the better fit: Cheapest good LLMs, Fastest LLMs–

Key differences

  • Claude Fable 5.1 (max) leads on quality: 67.2 vs 58.4.
  • Claude Fable 5.1 (max) is stronger in agents & tools, coding, human preference, knowledge, long context, maths, multimodal, reasoning.
  • Grok 4.20 (thinking) is stronger in instruction following.
  • Grok 4.20 (thinking) is 13× cheaper ($1.56 vs $20.00 per 1M blended).

At a glance

SpecClaude Fable 5.1Grok 4.20
DeveloperAnthropicSpaceXAI
Released1 Sep 202617 Feb 2026
Context window (tokens)1,000,0002,000,000
Compared atClaude Fable 5.1 (max)Grok 4.20 (thinking)
Open weightsNoNo
Price in / out / cached input per 1M$10.00 / $50.00 / $0.250$1.25 / $2.50 / $0.200

Category by category

Category scores on the BenchLeader scale: 50 is the average evaluated model, 15 points is one standard deviation. A gap under one point is called level.

CategoryClaude Fable 5.1 (max)Grok 4.20 (thinking)Leader
Reasoning71.061.0Claude Fable 5.1
Coding71.453.5Claude Fable 5.1
Agents & tools60.350.5Claude Fable 5.1
Maths72.553.9Claude Fable 5.1
Knowledge73.853.0Claude Fable 5.1
Instruction following–78.6not comparable
Human preference70.066.0Claude Fable 5.1
Multimodal67.158.3Claude Fable 5.1
Long context67.659.1Claude Fable 5.1

On one chart

Each domain on the index's own scale, where 50 is an average model. Click a domain to see the benchmarks behind it. Pick up to 5 models from the list.

2550 avg75ReasoningCodingAgents & toolsMathsKnowledgeLong contextMultimodalHumanpreferenceClaude Fable 5.1, Reasoning: 71.0Claude Fable 5.1, Coding: 71.4Claude Fable 5.1, Agents & tools: 60.3Claude Fable 5.1, Maths: 72.5Claude Fable 5.1, Knowledge: 73.8Claude Fable 5.1, Long context: 67.6Claude Fable 5.1, Multimodal: 67.1Claude Fable 5.1, Human preference: 70.0Grok 4.20, Reasoning: 61.0Grok 4.20, Coding: 53.5Grok 4.20, Agents & tools: 50.5Grok 4.20, Maths: 53.9Grok 4.20, Knowledge: 53.0Grok 4.20, Long context: 59.1Grok 4.20, Multimodal: 58.3Grok 4.20, Human preference: 66.0

Not drawn, measured for fewer than two of these models: Instruction following.

ModelIndex

Where sources disagree

Across the 23 benchmarks both have, Claude Fable 5.1 leads 23, Grok 4.20 leads 0. Every overall index that rates both puts Claude Fable 5.1 ahead.

Overall indexClaude Fable 5.1 (max)Grok 4.20 (thinking)Leader
BenchLeader Index67.258.4Claude Fable 5.1
Arena Text15041472Claude Fable 5.1

Each publisher runs its own tasks, harnesses and effort settings, so their overall verdicts can differ; BenchLeader reconciles them on one scale. † measured at another effort setting of the same model (the publisher did not test the one compared here).

Price, speed and latency

List prices blended at three input tokens per output token. Per-task prices use the token counts on the methodology page. Cost, tokens and time per benchmark task are measured: Artificial Analysis’ averages over its whole Intelligence Index run.

MeasureClaude Fable 5.1 (max)Grok 4.20 (thinking)
Blended price per 1M tokens$20.00$1.56
Input / output per 1M$10.00 / $50.00$1.25 / $2.50
Cached input per 1M$0.250$0.200
Price per task: chat reply$0.019$0.0013
Price per task: summarize a 30-page report$0.150$0.017
Price per task: code edit$0.135$0.011
Price per task: agentic coding session$0.800$0.085
Price per task: structured extraction$0.030$0.0030
Agentic coding session, input mostly cached$0.361$0.038
Cost per benchmark task (AA Index)$12.99–
Output tokens per task (AA Index)118k–
Of which reasoning71k–
Time per task (AA Index)22 min–
Output speed88 tok/s102 tok/s
Time to first answer183.7 s19.9 s
Time to a complete answer443.0 s50.3 s

Each model is compared at its best-ranked reasoning-effort setting. Claude Fable 5.1 (max) scores 67.2 and takes 184 s to its first answer token; Claude Fable 5.1 scores 66.4 in 3 s, Claude Fable 5.1 (xhigh) scores 65.4 in 65 s. Grok 4.20 (thinking) scores 58.4 and takes 20 s to its first answer token. Higher effort means more thinking before the answer: better scores, longer waits and more tokens billed. How reasoning effort changes scores and cost.

Every benchmark

155 benchmarks, grouped by category; each name links to the board and its leaders. † measured at another effort setting of the same model, shown for reference and not counted as a win.

MetricPublisherClaude Fable 5.1 (max)Grok 4.20 (thinking)
BenchLeader IndexBenchLeader67.258.4
Agents & tools scoreBenchLeader60.350.5
Coding scoreBenchLeader71.453.5
Human preference scoreBenchLeader70.066.0
Knowledge scoreBenchLeader73.853.0
Long context scoreBenchLeader67.659.1
Maths scoreBenchLeader72.553.9
Multimodal scoreBenchLeader67.158.3
Reasoning scoreBenchLeader71.061.0
Instruction following scoreBenchLeader–78.6
Blended price $/MBenchLeader$20.00$1.56
Output speedBenchLeader88 tok/s102 tok/s
Time to first answerBenchLeader183.7 s19.9 s
Context windowBenchLeader1,000,000 tokens2,000,000 tokens
Reasoning
GPQA DiamondEpoch AI Benchmarking Hub–89.3%
Humanity's Last ExamScale AI / CAIS46.5%†–
Arena Hard PromptsArena (LMArena)15241489
LiveBench 2.0 ReasoningLiveBench91.7%†–
LiveBench 1.0 ReasoningLiveBench91.7%–
GPQA Diamond (AA)Artificial Analysis93.7%91.1%
Humanity's Last Exam (AA)Artificial Analysis59.1%34.5%
HLE-Diamond (AA)Artificial Analysis60.1%–
GPQA Diamond (Vals)Vals AI93.4%†88.6%
Kagi LLM BenchmarkKagi LLM Benchmark–75.0%
ARC-AGI-1ARC Prize97.5%89.5%
ARC-AGI-2ARC Prize90.0%65.1%
ARC-AGI-3ARC Prize–0.1%
CritPtArtificial Analysis29.7%6.6%
CritPt v2 hard subset (AA)Artificial Analysis52.5%–
MysteryMechanismVals AI47.8%†–
Chess PuzzlesEpoch AI Benchmarking Hub48.0%29.0%
Mystery Game PuzzlesEpoch AI Benchmarking Hub58.0%–
CL-benchEpoch AI Benchmarking Hub–22.2%†
CL-bench LifeEpoch AI Benchmarking Hub–11.9%†
LMCAEpoch AI Benchmarking Hub65.5%†38.7%†
DTBenchEpoch AI Benchmarking Hub97.6%†90.1%†
ForecastBenchForecastBench–64.5%
Coding
SciCodeSciCode63.1%–
WeirdMLWeirdML92.9%52.3%†
Show all 155 benchmarks
MetricPublisherClaude Fable 5.1 (max)Grok 4.20 (thinking)
Coding
FrontierCodeCognition50.9%†–
GSO-BenchGSO-Bench88.2%†–
Arena CodingArena (LMArena)15371511
Arena WebDevArena (LMArena)17461376
LiveBench 2.0 CodingLiveBench97.7%†–
LiveBench 1.0 CodingLiveBench86.4%–
LiveCodeBenchVals AI90.5%†84.3%
IOIVals AI90.8%†–
SWE-bench (Vals)Vals AI–72.2%
Code MigrationVals AI54.6%†0.3%
ProgramBenchVals AI7.0%†–
SWE-bench MultimodalVals AI61.3%†–
Vibe Code Bench 1-100Vals AI28.0%†–
Vibe Code Bench v1.1Vals AI90.3%†4.1%
SWE Atlas: Codebase QnAScale AI SEAL60.0%†–
SWE Atlas: RefactoringScale AI SEAL56.7%†–
SWE Atlas: Test WritingScale AI SEAL67.0%†–
MirrorCodeEpoch AI Benchmarking Hub73.3%†–
CursorBenchCursor51.8%–
ALE-BenchEpoch AI Benchmarking Hub2143.2†1150.3†
FrontierSWEEpoch AI Benchmarking Hub56.3%–
Terminal-Bench 4.0 (AA)Artificial Analysis52.0%–
Terminal-Bench 2.1 (AA)Artificial Analysis91.4%–
Startrise FrontendStartrise77.1%†–
GameBench 2 OverallDuelLab GameBench 287.2†–
GameBench 2 by reasoning settingDuelLab GameBench 294.1†–
FrontierCode 1.1 (AA)Artificial Analysis49.0%–
FrontierCode 2.0 (AA)Artificial Analysis31.6%–
Agents & tools
Terminal-BenchTerminal-Bench57.9%57.3%†
Remote Labor IndexScale AI / CAIS17.9%†–
APEX-AgentsMercor68.6%†–
Arena AgentArena (LMArena)13.9–
LiveBench Long AgenticLiveBench77.9%†–
LiveBench BrowserLiveBench89.8%†–
LiveBench Agentic CodingLiveBench66.1%–
Terminal-Bench HardArtificial Analysis–37.9%
τ²-Bench Telecom (AA)Artificial Analysis–93.0%
Terminal-Bench 2.1 (Vals)Vals AI85.0%†44.2%
MCP AtlasScale AI SEAL87.2%†–
HiL-BenchScale AI SEAL61.5%†20.0%†
GDPval-AA v2.1, normalised scoreArtificial Analysis62.7%–
GDPval-AA v2.1Artificial Analysis1763–
τ³-Banking (AA)Artificial Analysis47.2%–
ITBench SRE (AA)Artificial Analysis49.5%–
Analyst Agent (AA)Artificial Analysis57.5%–
APEX-Agents (AA)Artificial Analysis–14.2%
CUA-benchVals AI13.2%–
CyberBenchVals AI70.4%†–
Finance Agent v2Vals AI58.9%†28.5%
Harvey's Legal Agent Benchmark v1Vals AI6.7%†0.0%
Legal Research BenchVals AI55.3%†13.9%
Robo-benchVals AI5.8%–
SkillsBenchVals AI61.5%†–
SREBenchVals AI22.9%†–
Tax Agent BenchVals AI49.2%†7.0%
Terminal-Bench 2.0 (Vals)Vals AI–40.5%
Terminal-Bench 4.0 (Vals)Vals AI58.1%†–
Terminal-Bench ScienceVals AI40.0%†–
Time Horizon Index: KSPVals AI63.3%†–
Arena SearchArena (LMArena)1233†–
Vending-Bench 2Andon Labs5421.6†4662.9†
AutomationBenchArtificial Analysis59.4%–
GDP.pdf (AA)Artificial Analysis26.2%–
Harvey LAB-AA v1.1Harvey6.4%–
AA-Briefcase v1.1Artificial Analysis1669–
GDPxGDPx by SemiAnalysis8.5%–
Terminal-Bench-Science 0.1 (AA)Artificial Analysis43.3%–
CWE-Bench (AA)Artificial Analysis50.8%–
DeepSec-Bench (AA)Artificial Analysis23.5%–
CyberGym end-to-end (AA)Artificial Analysis0.8%–
Maths
FrontierMath Tiers 1–3Epoch AI Benchmarking Hub90.2%44.9%
FrontierMath Tier 4Epoch AI Benchmarking Hub87.8%17.1%
OTIS Mock AIMEEpoch AI Benchmarking Hub100.0%92.2%
ProofBenchVals AI100.0%14.0%
LiveBench MathematicsLiveBench97.0%–
AIME (Vals)Vals AI–96.5%
Arena MathsArena (LMArena)15281465
Knowledge
SimpleQA VerifiedEpoch AI Benchmarking Hub70.8%30.2%
LiveBench 2.0 Data AnalysisLiveBench80.3%†–
LiveBench ResearchLiveBench82.0%†–
LiveBench 1.0 Data AnalysisLiveBench80.3%–
AA-Omniscience v1.1Artificial Analysis46.3–
MMLU-ProVals AI92.4%†86.3%
LegalBenchVals AI88.5%†77.7%
CorpFinVals AI–63.7%
TaxEvalVals AI76.0%†74.1%
MedQAVals AI–94.5%
PRBench FinanceScale AI SEAL50.8%†–
PRBench LegalScale AI SEAL51.6%†–
CaseLaw v2Vals AI–54.5%
Excel Modeling BenchmarkVals AI76.7%†11.7%
Excel Modeling Benchmark v1.1Vals AI76.7%†–
MedCodeVals AI53.5%†32.2%
MedScribeVals AI91.3%†63.4%
Public Benefits Bench v1.1Vals AI74.9%†–
EBR-benchEpoch AI Benchmarking Hub57.1%–
GDP.pdfEpoch AI Benchmarking Hub27.6%–
AA-Omniscience v1.1: accuracyArtificial Analysis68.4%–
AA-Omniscience v1.1: non-hallucinationArtificial Analysis30.0%–
Global-MMLU-Lite (AA)Artificial Analysis–89.5%
HealthBench Professional (AA)OpenAI57.8%–
Instruction following
LiveBench LanguageLiveBench89.5%–
LiveBench Instruction FollowingLiveBench73.0%–
IFBenchArtificial Analysis–81.2%
Arena Instruction FollowingArena (LMArena)15001447
Human preference
Arena TextArena (LMArena)15041472
Arena Creative WritingArena (LMArena)14891445
Arena Multi-turnArena (LMArena)14891479
Arena Longer QueriesArena (LMArena)15121466
Multimodal
Arena VisionArena (LMArena)13201262
LiveBench DesignLiveBench83.4%†–
MMMU-ProArtificial Analysis–74.6%
MMMU-Pro (Vals)Vals AI90.6%†83.5%
MortgageTaxVals AI70.8%†45.4%
Blueprint-Bench 2Epoch AI Benchmarking Hub41.9%†0.0%†
Code2Video-AAArtificial Analysis1325–
AA-3DArtificial Analysis1135–
Long context
AA-LCR v1.1Artificial Analysis85.3%69.0%
Arena DocumentArena (LMArena)14931439
MLCRArtificial Analysis15.6%–
Composite
Epoch Capabilities IndexEpoch AI Benchmarking Hub166.9†152.3†
LiveBench 2.0LiveBench85.7%†–
LiveBench 1.0LiveBench83.4%–
AA Intelligence Index v5.0Artificial Analysis49.2–
AA Intelligence Index v4.3.2Artificial Analysis53.425.7
AA Progress Index v1Artificial Analysis340.8281.9
Vals RSI IndexVals AI36.1%–
Vals Multimodal IndexVals AI–39.1%
AA Cyber IndexArtificial Analysis25.0–
Safety & honesty
FORTRESSScale AI SEAL13.7%†–

Data as of 2026-11-06. Best configuration of each model; every score links to its source on the model pages.

DuelLab GameBench 2, release gb2-20261103-09b2218cbd85 (https://benchmarks.duellab.org/releases/gb2-20261103-09b2218cbd85/), CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Scores mapped to BenchLeader model names; not endorsed by DuelLab.

What changed

  • Claude Fable 5.1 (max): 1 score revision.
  • Claude Fable 5.1 (max): 1 score revision.
  • Claude Fable 5.1 (max): 1 new result (MirrorCode).
  • Claude Fable 5.1 (max): 1 score revision.
  • Claude Fable 5.1 (max): BenchLeader Index 67.9 → 67.1.
  • Grok 4.20 (thinking): BenchLeader Index 58.9 → 58.4.
  • Claude Fable 5.1 (max): 5 new results (AA Intelligence Index v5.0, AA Progress Index v1, HLE-Diamond (AA)…); 3 score revisions; cost per task moved from $7.63/M to $13.04/M (71% up).
  • Grok 4.20 (thinking): 1 new result (AA Progress Index v1).
  • Grok 4.20 (thinking): 1 new result (Global-MMLU-Lite (AA)).
  • Claude Fable 5.1 (max): 2 new results (Robo-bench, Vals RSI Index).

Rankings: Best LLM overall · Best LLM for coding · Best LLM for agents · Best cheap LLMs

Claude Fable 5.1 vs Grok 4.20: questions

Is Claude Fable 5.1 better than Grok 4.20?
Claude Fable 5.1 (max) leads on quality: 67.2 vs 58.4. The BenchLeader Index combines every independent quality benchmark; Claude Fable 5.1 (max) is ahead overall as of 6 Nov 2026, but check the category scores for your use.
Claude Fable 5.1 vs Grok 4.20: which is cheaper, and will that change?
Grok 4.20 is cheaper today: $1.56 against $20.00 per million tokens, blended at three input tokens per output token. No price change has been announced for either.
Is Claude Fable 5.1 or Grok 4.20 better for coding?
Claude Fable 5.1 scores higher in coding (71 vs 54 on the category index, where 50 is average). On Arena WebDev, the top shared coding benchmark, it is 1746 for Claude Fable 5.1 against 1376 for Grok 4.20.
Which is faster, Claude Fable 5.1 or Grok 4.20?
Grok 4.20 streams ~1.5× faster (102 vs 88 output tokens per second, Artificial Analysis 7-day median).
Is Claude Fable 5.1 or Grok 4.20 better for agents and tool use?
Claude Fable 5.1 scores higher in agentic tasks (60 vs 51 on the category index, where 50 is average).
More questions (4)
Which is better for long documents?
Claude Fable 5.1 scores higher on long-context benchmarks (68 vs 59). Grok 4.20 accepts more context: 2,000,000 against 1,000,000 tokens for Claude Fable 5.1.
Which has lower latency?
Grok 4.20 answers first: 19.9 s against 183.7 s to the first answer token, as Artificial Analysis measures it. Reasoning effort drives most of this: a higher setting thinks longer before it answers.
Do independent benchmarks agree on Claude Fable 5.1 vs Grok 4.20?
Across the 23 benchmarks both have, Claude Fable 5.1 leads 23, Grok 4.20 leads 0. Every overall index that rates both puts Claude Fable 5.1 ahead.
When was Claude Fable 5.1 released?
Claude Fable 5.1 was released on 1 Sep 2026.