LLMBenchmark.ai

Enter opens the highlighted result. Esc closes.

Claude Fable 5.1 vs Grok 4.3

Updated October 21, 2026. 92 benchmarks have a result for both. Coding is ranked on the Vibe Coding Index; every other board is shown as published.

Replace Claude Fable 5.1 Replace Grok 4.3
Claude Fable 5.1Anthropic
Coding
89.1
Overall
53.4
Output $/M
$50.00
92
Grok 4.3xAI
Coding
22.5
Overall
24.9
Output $/M
$2.50
0
vs boards won of 92 shared

Decision reading

Pick Claude Fable 5.1 for coding: it scores 89.1 on the Vibe Coding Index against 22.5 for Grok 4.3.

Pick Grok 4.3 when output tokens cost 20.0x less.

Model AClaude Fable 5.1Anthropic89.1/1002 independent benchmarksNo cost per solved taskModel BGrok 4.3xAI22.5/1001 independent benchmark$0.31 per solved task
Shared results
92
Claude Fable 5.1 only
32
Grok 4.3 only
12
Like-for-like categories
8 of 9

Shared results can support a head-to-head reading. Results only one model has describe coverage, not superiority.

Which one for your work

Each card is decided by one number both models carry. Where only one has it, the card says so and makes no call.

At a glance

Coding index
Claude Fable 5.1 89.1 from 2 benchmarks, Grok 4.3 22.5 from 1 benchmark.
Widest category
Math, 44.1 points apart on average over 6 shared benchmarks.
Widest single gap
ProofBench: Claude Fable 5.1 100.0% against Grok 4.3 11.0%, 89.0 points apart on a 0 to 100 scale.
Output price
Claude Fable 5.1 $50.00 against Grok 4.3 $2.50 per million output tokens, 20.0x apart.
Context window
Both take 1M tokens.

Benchmark by benchmark

First the score: boards each model leads, per category, where both have a result. Then every board, a category to a fold; bars are each result on a 0 to 100 scale, so compare the two in a row, not one row with another.

Boards won, where both have a result
CategoryClaude Fable 5.1BarsGrok 4.3Ties
Coding160
Intelligence10
Agentic work120
Reasoning100
Math60
Knowledge100
Web design80
General290
All shared boards920
CodingLike-for-likeFour of these boards feed the Vibe Coding Index160
Coding benchmarks for Claude Fable 5.1 and Grok 4.3
BenchmarkClaude Fable 5.1Grok 4.3Leader
LiveBench coding97.7%Not measuredOnly Claude Fable 5.1 measured
LMArena WebDev17431358Claude Fable 5.1
AA Coding Index81.642.2Claude Fable 5.1
LiveCodeBench (Vals AI)90.5%84.5%Claude Fable 5.1
SWE-bench Verified (Vals AI)Not measured71.4%Only Grok 4.3 measured
Terminal-Bench 4 (Vals AI)58.1%Not measuredOnly Claude Fable 5.1 measured
Vibe Code Bench (Vals AI)90.3%19.4%Claude Fable 5.1
Code migration (Vals AI)54.6%6.8%Claude Fable 5.1
ProgramBench (Vals AI)7.0%0.0%Claude Fable 5.1
IOI (Vals AI)90.8%Not measuredOnly Claude Fable 5.1 measured
Terminal-Bench 2.1 (Vals AI)85.0%42.0%Claude Fable 5.1
SWE-bench Multimodal (Vals AI)61.3%Not measuredOnly Claude Fable 5.1 measured
Vibe Code Bench 1-100 (Vals AI)28.0%Not measuredOnly Claude Fable 5.1 measured
SkillsBench (Vals AI)61.5%40.6%Claude Fable 5.1
CyberBench (Vals AI)70.4%Not measuredOnly Claude Fable 5.1 measured
SciCode63.1%48.3%Claude Fable 5.1
Terminal-Bench Hard (Artificial Analysis run)Not measured37.9%Only Grok 4.3 measured
FrontierCode50.9%Not measuredOnly Claude Fable 5.1 measured
FrontierSWE56.3%Not measuredOnly Claude Fable 5.1 measured
GSO-Bench88.2%Not measuredOnly Claude Fable 5.1 measured
WeirdML92.9%49.9%Claude Fable 5.1
MirrorCode73.3%Not measuredOnly Claude Fable 5.1 measured
ALE-Bench2143.2944.2Claude Fable 5.1
LMArena Text: coding15321415Claude Fable 5.1
LMArena Text: software and IT15301416Claude Fable 5.1
LMArena WebDev: React17921353Claude Fable 5.1
LMArena WebDev: HTML16841367Claude Fable 5.1
LMArena WebDev: from an image17221375Claude Fable 5.1
Neither model has a result on the other 10 boards here
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index10
Intelligence benchmarks for Claude Fable 5.1 and Grok 4.3
BenchmarkClaude Fable 5.1Grok 4.3Leader
AA Intelligence Index53.424.9Claude Fable 5.1
Epoch Capabilities Index166.5Not measuredOnly Claude Fable 5.1 measured
Agentic workLike-for-likePublic boards, shown as published, kept out of the index120
Agentic work benchmarks for Claude Fable 5.1 and Grok 4.3
BenchmarkClaude Fable 5.1Grok 4.3Leader
AA Agentic Index57.915.5Claude Fable 5.1
Design Arena: agents building web apps13181126Claude Fable 5.1
Design Arena: agents building full-stack apps13261006Claude Fable 5.1
Design Arena: agents building mobile apps12671059Claude Fable 5.1
Design Arena: agents building Android appsNot measured967Only Grok 4.3 measured
Design Arena: agents building Godot games1327914Claude Fable 5.1
Design Arena: agents building gamesNot measured1007Only Grok 4.3 measured
Design Arena: HTML slidesNot measured1008Only Grok 4.3 measured
Design Arena: PowerPoint slides13281012Claude Fable 5.1
Design Arena: spreadsheets1374Not measuredOnly Claude Fable 5.1 measured
LiveBench research82.0%Not measuredOnly Claude Fable 5.1 measured
LiveBench browser100.0%Not measuredOnly Claude Fable 5.1 measured
LiveBench long agentic80.8%Not measuredOnly Claude Fable 5.1 measured
SREBench (Vals AI)22.9%Not measuredOnly Claude Fable 5.1 measured
Finance Agent (Vals AI)58.9%37.7%Claude Fable 5.1
Tax Agent Bench (Vals AI)49.2%6.2%Claude Fable 5.1
Legal Research Bench (Vals AI)55.3%15.4%Claude Fable 5.1
Excel Modeling Benchmark (Vals AI)76.7%18.4%Claude Fable 5.1
Terminal-Bench-Science (Vals AI)40.0%Not measuredOnly Claude Fable 5.1 measured
Time Horizon Index (Vals AI)63.3%Not measuredOnly Claude Fable 5.1 measured
CUA-bench (Vals AI)13.2%Not measuredOnly Claude Fable 5.1 measured
Robo-bench (Vals AI)5.8%Not measuredOnly Claude Fable 5.1 measured
τ²-Bench TelecomNot measured97.7%Only Grok 4.3 measured
APEX-Agents68.6%Not measuredOnly Claude Fable 5.1 measured
Remote Labor Index17.9%Not measuredOnly Claude Fable 5.1 measured
SpireClimb2.0%Not measuredOnly Claude Fable 5.1 measured
Vending-Bench 2$5,422$35Claude Fable 5.1
LMArena Search12461166Claude Fable 5.1
Neither model has a result on the other 11 boards here
ReasoningLike-for-likePublic boards, shown as published, kept out of the index100
Reasoning benchmarks for Claude Fable 5.1 and Grok 4.3
BenchmarkClaude Fable 5.1Grok 4.3Leader
GPQA Diamond93.4%91.4%Claude Fable 5.1
LiveBench reasoning91.7%Not measuredOnly Claude Fable 5.1 measured
MysteryMechanism (Vals AI)47.8%Not measuredOnly Claude Fable 5.1 measured
MMMU Pro (Vals AI)90.6%83.1%Claude Fable 5.1
GPQA Diamond (Artificial Analysis run)93.7%90.1%Claude Fable 5.1
Humanity's Last Exam (Artificial Analysis run)59.1%37.2%Claude Fable 5.1
GPQA Diamond (Epoch AI run)Not measured88.8%Only Grok 4.3 measured
ARC-AGI97.5%Not measuredOnly Claude Fable 5.1 measured
ARC-AGI-290.0%Not measuredOnly Claude Fable 5.1 measured
Chess puzzles48.0%18.0%Claude Fable 5.1
Mystery game puzzles58.0%Not measuredOnly Claude Fable 5.1 measured
EBR-bench57.1%Not measuredOnly Claude Fable 5.1 measured
LMArena Text: hard prompts15281396Claude Fable 5.1
LMArena Text: expert15441384Claude Fable 5.1
LMArena Text: hard prompts in English15221402Claude Fable 5.1
LMArena Vision: diagrams13431241Claude Fable 5.1
LMArena Vision: homework13451241Claude Fable 5.1
Neither model has a result on the other 4 boards here
MathLike-for-likePublic boards, shown as published, kept out of the index60
Math benchmarks for Claude Fable 5.1 and Grok 4.3
BenchmarkClaude Fable 5.1Grok 4.3Leader
OTIS Mock AIME100.0%93.3%Claude Fable 5.1
FrontierMath, tiers 1 to 390.2%42.8%Claude Fable 5.1
FrontierMath, tier 487.8%14.6%Claude Fable 5.1
ProofBench100.0%11.0%Claude Fable 5.1
LMArena Text: math15311387Claude Fable 5.1
LMArena Text: mathematical work15411396Claude Fable 5.1
Neither model has a result on the other 7 boards here
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index100
Knowledge benchmarks for Claude Fable 5.1 and Grok 4.3
BenchmarkClaude Fable 5.1Grok 4.3Leader
MMLU Pro92.4%85.8%Claude Fable 5.1
LegalBench (Vals AI)88.5%84.5%Claude Fable 5.1
CaseLaw (Vals AI)Not measured79.3%Only Grok 4.3 measured
CorpFin (Vals AI)Not measured68.5%Only Grok 4.3 measured
TaxEval (Vals AI)76.0%70.8%Claude Fable 5.1
MortgageTax (Vals AI)70.8%48.3%Claude Fable 5.1
MedCode (Vals AI)53.5%38.1%Claude Fable 5.1
SimpleQA Verified70.8%33.2%Claude Fable 5.1
LMArena Text: science15321399Claude Fable 5.1
LMArena Text: medicine and healthcare15311384Claude Fable 5.1
LMArena Text: legal and government15141386Claude Fable 5.1
LMArena Text: business and finance14931381Claude Fable 5.1
Neither model has a result on the other 5 boards here
Web designLike-for-likePublic boards, shown as published, kept out of the index80
Web design benchmarks for Claude Fable 5.1 and Grok 4.3
BenchmarkClaude Fable 5.1Grok 4.3Leader
Design Arena: websites13131196Claude Fable 5.1
Design Arena: UI components13381192Claude Fable 5.1
Design Arena: game dev13821174Claude Fable 5.1
Design Arena: data viz13441180Claude Fable 5.1
Design Arena: 3D13931125Claude Fable 5.1
Design Arena: all code categories13361187Claude Fable 5.1
Design Arena: SVG13011081Claude Fable 5.1
Design Arena: ASCII art13241125Claude Fable 5.1
LiveBench design83.4%Not measuredOnly Claude Fable 5.1 measured
GeneralLike-for-likePublic boards, shown as published, kept out of the index290
General benchmarks for Claude Fable 5.1 and Grok 4.3
BenchmarkClaude Fable 5.1Grok 4.3Leader
LiveBench data analysis80.3%Not measuredOnly Claude Fable 5.1 measured
Public Benefits Bench (Vals AI)74.9%51.7%Claude Fable 5.1
SAGE (Vals AI)48.5%19.7%Claude Fable 5.1
MedScribe (Vals AI)91.3%74.4%Claude Fable 5.1
Vals Multimodal IndexNot measured43.3%Only Grok 4.3 measured
IFBenchNot measured83.3%Only Grok 4.3 measured
Long context reasoning (AA-LCR)85.3%75.0%Claude Fable 5.1
DTBench97.6%90.7%Claude Fable 5.1
LMCA65.5%38.3%Claude Fable 5.1
Furniture assembly70.0%Not measuredOnly Claude Fable 5.1 measured
LMArena Text15121397Claude Fable 5.1
LMArena Text: instruction following15181366Claude Fable 5.1
LMArena Text: creative writing15091380Claude Fable 5.1
LMArena Vision13191229Claude Fable 5.1
LMArena Text: English15061404Claude Fable 5.1
LMArena Text: non-English15081385Claude Fable 5.1
LMArena Text: Chinese15841422Claude Fable 5.1
LMArena Text: German14991395Claude Fable 5.1
LMArena Text: Japanese15621379Claude Fable 5.1
LMArena Text: Korean15171354Claude Fable 5.1
LMArena Text: French15231411Claude Fable 5.1
LMArena Text: Spanish15201399Claude Fable 5.1
LMArena Text: Russian15201399Claude Fable 5.1
LMArena Text: Polish15251398Claude Fable 5.1
LMArena Text: multi-turn14931406Claude Fable 5.1
LMArena Text: longer queries15241393Claude Fable 5.1
LMArena Text: writing and language15101385Claude Fable 5.1
LMArena Text: entertainment and media14971370Claude Fable 5.1
LMArena Vision: English13131235Claude Fable 5.1
LMArena Vision: Chinese13911257Claude Fable 5.1
LMArena Vision: reading text13271235Claude Fable 5.1
LMArena Vision: humor13181222Claude Fable 5.1
LMArena Vision: recognizing thingsNot measured1217Only Grok 4.3 measured
LMArena Vision: creative writing13301237Claude Fable 5.1
Neither model has a result on the other 12 boards here
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
Image generation benchmarks for Claude Fable 5.1 and Grok 4.3
BenchmarkClaude Fable 5.1Grok 4.3Leader
Neither model has a result on 5 boards here

What each workload costs

Three fixed token mixes at each model's listed price, so per-token rates become a bill.

Chat turn

1K input + 500 output tokens

Claude Fable 5.1$0.035Fits in one request
Grok 4.3$0.0025Fits in one request

Grok 4.3 costs less

Repository review

50K input + 3K output tokens

Claude Fable 5.1$0.650Fits in one request
Grok 4.3$0.070Fits in one request

Grok 4.3 costs less

Agent loop

200K input + 10K output tokens

Claude Fable 5.1$2.50Fits in one request
Grok 4.3$0.275Fits in one request

Grok 4.3 costs less

Listed OpenRouter rates, without cache or batch discounts. A workload that does not fit a model's context window would need splitting.

Specification differences

The leading value in a row is marked; a row with a missing value names no leader. Our two rows are marked in red.

Specifications of Claude Fable 5.1 and Grok 4.3
SpecificationAnthropic Claude Fable 5.1SpaceXAI Grok 4.3
MakerAnthropicxAI
WeightsNo public weights listedNo public weights listed
ReleasedSeptember 1, 2026April 30, 2026
Context window1M1M
Input $/Mtok$10.00$1.25
Output $/Mtok$50.00$2.50
Coding index89.122.5
Independent measurements behind it21
Cost per solved taskNot computable$0.31
SourceOpenRouter listingOpenRouter listing

Questions

Is Claude Fable 5.1 better than Grok 4.3 for coding?

Pick Claude Fable 5.1 for coding: it scores 89.1 on the Vibe Coding Index against 22.5 for Grok 4.3. Pick Grok 4.3 when output tokens cost 20.0x less.

Which is cheaper, Claude Fable 5.1 or Grok 4.3?

Claude Fable 5.1 costs $10.00 per million input tokens and $50.00 per million output tokens; Grok 4.3 costs $1.25 and $2.50. Cost per solved task is known for Grok 4.3 only.

Which has the bigger context window, Claude Fable 5.1 or Grok 4.3?

Neither: both take 1M tokens.

How many benchmarks is the Claude Fable 5.1 vs Grok 4.3 comparison based on?

92 benchmarks have a result for both models as of October 21, 2026. Claude Fable 5.1's coding index rests on 2 independent benchmarks and Grok 4.3's on 1. Where only one model has a result, the page says so instead of naming a winner.

Compare next