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Claude Fable 5 vs Grok 4.3

Claude Fable 5 leads Grok 4.3 on coding, 79.3 to 37.4 on the Vibe Coding Index, and Grok 4.3 costs 20.0x less per output token ($2.50 vs $50.00 per million). Updated October 21, 2026; 101 benchmarks have a result for both.

Replace Claude Fable 5 Replace Grok 4.3
Claude Fable 5Anthropic
Coding
79.3
Overall
79.0
Output $/M
$50.00
99
Grok 4.3xAI
Coding
37.4
Overall
53.1
Output $/M
$2.50
2
vs boards won of 101 shared

Claude Fable 5 or Grok 4.3: which to pick

Pick Claude Fable 5 for coding: it scores 79.3 on the Vibe Coding Index against 37.4 for Grok 4.3.

Pick Grok 4.3 for output tokens 20.0x cheaper ($2.50 vs $50.00 per million) and a lower cost per solved task ($0.31 against $2.16).

Model AClaude Fable 5Anthropic79.3/1006 independent benchmarks$2.16 per solved taskModel BGrok 4.3xAI37.4/1003 independent benchmarks$0.31 per solved task
Shared results
101
Claude Fable 5 only
26
Grok 4.3 only
3
Like-for-like categories
8 of 9

Only benchmarks that tested both models count toward a pick; a result only one model has is shown but not compared.

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 79.3 from 6 benchmarks, Grok 4.3 37.4 from 3 benchmarks.
Widest category
Math, 42.0 points apart on average over 6 shared benchmarks.
Widest single gap
ProofBench: Claude Fable 5 95.0% against Grok 4.3 11.0%, 84.0 points apart on a 0 to 100 scale.
Output price
Claude Fable 5 $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 5BarsGrok 4.3Ties
Coding170
Intelligence10
Agentic work160
Reasoning101
Math60
Knowledge110
Web design80
General301
All shared boards992
CodingLike-for-likeSix of these boards feed the Vibe Coding Index170
Coding benchmarks for Claude Fable 5 and Grok 4.3
BenchmarkClaude Fable 5Grok 4.3Leader
LiveBench coding98.3%Not measuredOnly Claude Fable 5 measured
LMArena WebDev16241358Claude Fable 5
AA Coding Index76.542.2Claude Fable 5
LiveCodeBench (Vals AI)89.8%84.5%Claude Fable 5
SWE-bench Verified (Vals AI)95.0%71.4%Claude Fable 5
Terminal-Bench 4 (Vals AI)41.4%Not measuredOnly Claude Fable 5 measured
Vibe Code Bench (Vals AI)90.3%19.4%Claude Fable 5
Code migration (Vals AI)55.1%6.8%Claude Fable 5
ProgramBench (Vals AI)2.0%0.0%Claude Fable 5
Terminal-Bench 2.1 (Vals AI)80.5%42.0%Claude Fable 5
SkillsBench (Vals AI)Not measured40.6%Only Grok 4.3 measured
SciCode61.0%48.3%Claude Fable 5
Terminal-Bench Hard (Artificial Analysis run)62.9%37.9%Claude Fable 5
FrontierCode53.5%Not measuredOnly Claude Fable 5 measured
FrontierSWE47.0%Not measuredOnly Claude Fable 5 measured
GSO-Bench78.4%Not measuredOnly Claude Fable 5 measured
WeirdML91.9%49.9%Claude Fable 5
MirrorCode63.9%Not measuredOnly Claude Fable 5 measured
ALE-Bench2041.3944.2Claude Fable 5
LMArena Text: coding15181415Claude Fable 5
LMArena Text: software and IT15131416Claude Fable 5
LMArena WebDev: React16311353Claude Fable 5
LMArena WebDev: HTML16511367Claude Fable 5
LMArena WebDev: from an image16231375Claude Fable 5
Neither model has a result on the other 15 boards here
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index10
Intelligence benchmarks for Claude Fable 5 and Grok 4.3
BenchmarkClaude Fable 5Grok 4.3Leader
AA Intelligence Index49.624.9Claude Fable 5
Epoch Capabilities Index163.4Not measuredOnly Claude Fable 5 measured
Agentic workLike-for-likePublic boards, shown as published, kept out of the index160
Agentic work benchmarks for Claude Fable 5 and Grok 4.3
BenchmarkClaude Fable 5Grok 4.3Leader
AA Agentic Index50.715.5Claude Fable 5
Design Arena: agents building web apps12611126Claude Fable 5
Design Arena: agents building full-stack apps12801006Claude Fable 5
Design Arena: agents building mobile apps12641059Claude Fable 5
Design Arena: agents building Android apps1283961Claude Fable 5
Design Arena: agents building Godot games1292914Claude Fable 5
Design Arena: agents building games12851007Claude Fable 5
Design Arena: HTML slides12771008Claude Fable 5
Design Arena: PowerPoint slides12951013Claude Fable 5
LiveBench research86.9%Not measuredOnly Claude Fable 5 measured
LiveBench browser92.0%Not measuredOnly Claude Fable 5 measured
LiveBench long agentic53.2%Not measuredOnly Claude Fable 5 measured
Finance Agent (Vals AI)56.3%37.7%Claude Fable 5
Tax Agent Bench (Vals AI)38.3%6.2%Claude Fable 5
Legal Research Bench (Vals AI)49.5%15.4%Claude Fable 5
Excel Modeling Benchmark (Vals AI)73.7%18.4%Claude Fable 5
Terminal-Bench-Science (Vals AI)15.7%Not measuredOnly Claude Fable 5 measured
τ²-Bench Telecom98.5%97.7%Claude Fable 5
APEX-Agents63.6%Not measuredOnly Claude Fable 5 measured
Remote Labor Index16.1%Not measuredOnly Claude Fable 5 measured
PostTrainBench41.8%Not measuredOnly Claude Fable 5 measured
Vending-Bench 2$5,680$35Claude Fable 5
LMArena Search12291166Claude Fable 5
Neither model has a result on the other 18 boards here
ReasoningLike-for-likePublic boards, shown as published, kept out of the index101
Reasoning benchmarks for Claude Fable 5 and Grok 4.3
BenchmarkClaude Fable 5Grok 4.3Leader
GPQA Diamond93.2%91.4%Claude Fable 5
LiveBench reasoning89.7%Not measuredOnly Claude Fable 5 measured
MMMU Pro (Vals AI)89.3%83.1%Claude Fable 5
GPQA Diamond (Artificial Analysis run)92.6%90.1%Claude Fable 5
Humanity's Last Exam (Artificial Analysis run)55.5%37.2%Claude Fable 5
GPQA Diamond (Epoch AI run)85.9%88.8%Grok 4.3
ARC-AGI98.5%Not measuredOnly Claude Fable 5 measured
ARC-AGI-289.2%Not measuredOnly Claude Fable 5 measured
SimpleBench81.9%Not measuredOnly Claude Fable 5 measured
Chess puzzles47.0%18.0%Claude Fable 5
Mystery game puzzles52.0%Not measuredOnly Claude Fable 5 measured
EBR-bench39.5%Not measuredOnly Claude Fable 5 measured
LMArena Text: hard prompts15071396Claude Fable 5
LMArena Text: expert15341384Claude Fable 5
LMArena Text: hard prompts in English15091402Claude Fable 5
LMArena Vision: diagrams13571241Claude Fable 5
LMArena Vision: homework13611241Claude Fable 5
Kagi LLM Benchmark91.4%Not measuredOnly Claude Fable 5 measured
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 and Grok 4.3
BenchmarkClaude Fable 5Grok 4.3Leader
OTIS Mock AIME100.0%93.3%Claude Fable 5
FrontierMath, tiers 1 to 387.0%42.8%Claude Fable 5
FrontierMath, tier 490.2%14.6%Claude Fable 5
ProofBench95.0%11.0%Claude Fable 5
LMArena Text: math15161387Claude Fable 5
LMArena Text: mathematical work15151396Claude Fable 5
Neither model has a result on the other 7 boards here
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index110
Knowledge benchmarks for Claude Fable 5 and Grok 4.3
BenchmarkClaude Fable 5Grok 4.3Leader
MMLU Pro91.5%85.8%Claude Fable 5
LegalBench (Vals AI)88.6%84.5%Claude Fable 5
CaseLaw (Vals AI)Not measured79.3%Only Grok 4.3 measured
CorpFin (Vals AI)71.8%68.5%Claude Fable 5
TaxEval (Vals AI)76.9%70.8%Claude Fable 5
MortgageTax (Vals AI)68.9%48.3%Claude Fable 5
MedCode (Vals AI)56.1%38.1%Claude Fable 5
SimpleQA Verified70.7%33.2%Claude Fable 5
LMArena Text: science15061399Claude Fable 5
LMArena Text: medicine and healthcare14801384Claude Fable 5
LMArena Text: legal and government14981386Claude Fable 5
LMArena Text: business and finance14801381Claude Fable 5
Neither model has a result on the other 6 boards here
Web designLike-for-likePublic boards, shown as published, kept out of the index80
Web design benchmarks for Claude Fable 5 and Grok 4.3
BenchmarkClaude Fable 5Grok 4.3Leader
Design Arena: websites12961196Claude Fable 5
Design Arena: UI components13191192Claude Fable 5
Design Arena: game dev13351174Claude Fable 5
Design Arena: data viz13041179Claude Fable 5
Design Arena: 3D13191125Claude Fable 5
Design Arena: all code categories13101187Claude Fable 5
Design Arena: SVG13021081Claude Fable 5
Design Arena: ASCII art13291125Claude Fable 5
LiveBench design84.7%Not measuredOnly Claude Fable 5 measured
GeneralLike-for-likePublic boards, shown as published, kept out of the index301
General benchmarks for Claude Fable 5 and Grok 4.3
BenchmarkClaude Fable 5Grok 4.3Leader
LiveBench data analysis80.5%Not measuredOnly Claude Fable 5 measured
Public Benefits Bench (Vals AI)70.4%51.7%Claude Fable 5
SAGE (Vals AI)51.9%19.7%Claude Fable 5
MedScribe (Vals AI)88.5%74.4%Claude Fable 5
Vals Multimodal Index74.2%43.3%Claude Fable 5
IFBench63.5%83.3%Grok 4.3
Long context reasoning (AA-LCR)82.3%75.0%Claude Fable 5
DTBench98.4%90.7%Claude Fable 5
LMCA61.2%38.3%Claude Fable 5
Surface Evolver Bench95.0%Not measuredOnly Claude Fable 5 measured
Furniture assembly35.8%Not measuredOnly Claude Fable 5 measured
LMArena Text14911397Claude Fable 5
LMArena Text: instruction following15021366Claude Fable 5
LMArena Text: creative writing14941380Claude Fable 5
LMArena Vision13251229Claude Fable 5
LMArena Text: English14981404Claude Fable 5
LMArena Text: non-English14821385Claude Fable 5
LMArena Text: Chinese15431422Claude Fable 5
LMArena Text: German14861395Claude Fable 5
LMArena Text: Japanese15041379Claude Fable 5
LMArena Text: Korean14871354Claude Fable 5
LMArena Text: French15051411Claude Fable 5
LMArena Text: Spanish14981399Claude Fable 5
LMArena Text: Russian15031399Claude Fable 5
LMArena Text: Polish14941398Claude Fable 5
LMArena Text: multi-turn15041406Claude Fable 5
LMArena Text: longer queries15101393Claude Fable 5
LMArena Text: writing and language15011385Claude Fable 5
LMArena Text: entertainment and media14821370Claude Fable 5
LMArena Vision: English13231235Claude Fable 5
LMArena Vision: Chinese13731257Claude Fable 5
LMArena Vision: reading text13371235Claude Fable 5
LMArena Vision: humor13411222Claude Fable 5
LMArena Vision: recognizing thingsNot measured1217Only Grok 4.3 measured
LMArena Vision: creative writing13381237Claude Fable 5
LMArena Document1496Not measuredOnly Claude Fable 5 measured
Neither model has a result on the other 10 boards here
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
Image generation benchmarks for Claude Fable 5 and Grok 4.3
BenchmarkClaude Fable 5Grok 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$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$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$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 and Grok 4.3
SpecificationAnthropic Claude Fable 5SpaceXAI Grok 4.3
MakerAnthropicxAI
WeightsNo public weights listedNo public weights listed
ReleasedJune 9, 2026April 30, 2026
Context window1M1M
Input $/Mtok$10.00$1.25
Output $/Mtok$50.00$2.50
Coding index79.337.4
Independent measurements behind it63
Cost per solved task$2.16$0.31
SourceOpenRouter listingOpenRouter listing

Questions

Is Claude Fable 5 better than Grok 4.3 for coding?

Pick Claude Fable 5 for coding: it scores 79.3 on the Vibe Coding Index against 37.4 for Grok 4.3. Pick Grok 4.3 for output tokens 20.0x cheaper ($2.50 vs $50.00 per million) and a lower cost per solved task ($0.31 against $2.16).

Which is cheaper, Claude Fable 5 or Grok 4.3?

Claude Fable 5 costs $10.00 per million input tokens and $50.00 per million output tokens; Grok 4.3 costs $1.25 and $2.50. Per solved SWE-bench Verified task, Claude Fable 5 costs $2.16 and Grok 4.3 $0.31.

Which has the bigger context window, Claude Fable 5 or Grok 4.3?

Neither: both take 1M tokens.

How many benchmarks is the Claude Fable 5 vs Grok 4.3 comparison based on?

101 benchmarks have a result for both models as of October 21, 2026. Claude Fable 5's coding index rests on 6 independent benchmarks and Grok 4.3's on 3. Where only one model has a result, the page says so instead of naming a winner.

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