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Claude Opus 5.5 vs Grok 4.3

Claude Opus 5.5 leads Grok 4.3 on coding, 88.8 to 37.4 on the Vibe Coding Index, and Grok 4.3 costs 8.0x less per output token ($2.50 vs $20.00 per million). Updated October 22, 2026; 73 benchmarks have a result for both.

Replace Claude Opus 5.5 Replace Grok 4.3
Claude Opus 5.5Anthropic
Coding
88.8
Overall
87.1
Output $/M
$20.00
73
Grok 4.3xAI
Coding
37.4
Overall
53.1
Output $/M
$2.50
0
vs boards won of 73 shared

Claude Opus 5.5 or Grok 4.3: which to pick

Pick Claude Opus 5.5 for coding: it scores 88.8 on the Vibe Coding Index against 37.4 for Grok 4.3.

Pick Grok 4.3 for output tokens 8.0x cheaper ($2.50 vs $20.00 per million).

Model AClaude Opus 5.5Anthropic88.8/1005 independent benchmarksNo cost per solved taskModel BGrok 4.3xAI37.4/1003 independent benchmarks$0.31 per solved task
Shared results
73
Claude Opus 5.5 only
36
Grok 4.3 only
32
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 Opus 5.5 88.8 from 5 benchmarks, Grok 4.3 37.4 from 3 benchmarks.
Widest category
Math, 44.4 points apart on average over 6 shared benchmarks.
Widest single gap
ProofBench: Claude Opus 5.5 100.0% against Grok 4.3 11.0%, 89.0 points apart on a 0 to 100 scale.
Output price
Claude Opus 5.5 $20.00 against Grok 4.3 $2.50 per million output tokens, 8.0x 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 Opus 5.5BarsGrok 4.3Ties
Coding120
Intelligence10
Agentic work90
Reasoning80
Math60
Knowledge60
Web design70
General240
All shared boards730
CodingLike-for-likeSix of these boards feed the Vibe Coding Index120
Coding benchmarks for Claude Opus 5.5 and Grok 4.3
BenchmarkClaude Opus 5.5Grok 4.3Leader
LiveBench coding96.3%Not measuredOnly Claude Opus 5.5 measured
LMArena WebDev18071358Claude Opus 5.5
AA Coding IndexNot measured42.2Only Grok 4.3 measured
LiveCodeBench (Vals AI)Not measured84.5%Only Grok 4.3 measured
SWE-bench Verified (Vals AI)Not measured71.4%Only Grok 4.3 measured
Terminal-Bench 4 (Vals AI)65.2%Not measuredOnly Claude Opus 5.5 measured
Vibe Code Bench (Vals AI)90.3%19.4%Claude Opus 5.5
Code migration (Vals AI)66.7%6.8%Claude Opus 5.5
ProgramBench (Vals AI)18.5%0.0%Claude Opus 5.5
IOI (Vals AI)95.1%Not measuredOnly Claude Opus 5.5 measured
Terminal-Bench 2.1 (Vals AI)87.6%42.0%Claude Opus 5.5
SWE-bench Multimodal (Vals AI)70.2%Not measuredOnly Claude Opus 5.5 measured
Vibe Code Bench 1-100 (Vals AI)30.4%Not measuredOnly Claude Opus 5.5 measured
SkillsBench (Vals AI)Not measured40.6%Only Grok 4.3 measured
CyberBench (Vals AI)74.6%Not measuredOnly Claude Opus 5.5 measured
SciCode66.9%48.3%Claude Opus 5.5
Terminal-Bench Hard (Artificial Analysis run)Not measured37.9%Only Grok 4.3 measured
FrontierCode54.6%Not measuredOnly Claude Opus 5.5 measured
FrontierSWE62.3%Not measuredOnly Claude Opus 5.5 measured
WeirdMLNot measured49.9%Only Grok 4.3 measured
MirrorCode77.4%Not measuredOnly Claude Opus 5.5 measured
ALE-Bench2147.4944.2Claude Opus 5.5
LMArena Text: coding15451415Claude Opus 5.5
LMArena Text: software and IT15381416Claude Opus 5.5
LMArena WebDev: React18551353Claude Opus 5.5
LMArena WebDev: HTML17531367Claude Opus 5.5
LMArena WebDev: from an image17531375Claude Opus 5.5
SciCode18.5%Not measuredOnly Claude Opus 5.5 measured
Neither model has a result on the other 11 boards here
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index10
Intelligence benchmarks for Claude Opus 5.5 and Grok 4.3
BenchmarkClaude Opus 5.5Grok 4.3Leader
AA Intelligence Index57.624.9Claude Opus 5.5
Epoch Capabilities Index168.8Not measuredOnly Claude Opus 5.5 measured
Agentic workLike-for-likePublic boards, shown as published, kept out of the index90
Agentic work benchmarks for Claude Opus 5.5 and Grok 4.3
BenchmarkClaude Opus 5.5Grok 4.3Leader
AA Agentic IndexNot measured15.5Only Grok 4.3 measured
Design Arena: agents building web apps13161126Claude Opus 5.5
Design Arena: agents building full-stack appsNot measured1006Only Grok 4.3 measured
Design Arena: agents building mobile apps13081058Claude Opus 5.5
Design Arena: agents building Android appsNot measured962Only Grok 4.3 measured
Design Arena: agents building Godot gamesNot measured914Only Grok 4.3 measured
Design Arena: agents building gamesNot measured1007Only Grok 4.3 measured
Design Arena: HTML slidesNot measured959Only Grok 4.3 measured
Design Arena: PowerPoint slidesNot measured988Only Grok 4.3 measured
Design Arena: spreadsheets1368879Claude Opus 5.5
LiveBench research85.0%Not measuredOnly Claude Opus 5.5 measured
LiveBench browser80.0%Not measuredOnly Claude Opus 5.5 measured
LiveBench long agentic85.0%Not measuredOnly Claude Opus 5.5 measured
SREBench (Vals AI)33.6%Not measuredOnly Claude Opus 5.5 measured
Finance Agent (Vals AI)58.6%37.7%Claude Opus 5.5
Tax Agent Bench (Vals AI)45.6%6.2%Claude Opus 5.5
Legal Research Bench (Vals AI)50.5%15.4%Claude Opus 5.5
Harvey's Legal Agent Benchmark (Vals AI)9.2%Not measuredOnly Claude Opus 5.5 measured
Excel Modeling Benchmark (Vals AI)75.9%18.4%Claude Opus 5.5
BioMysteryBench (Vals AI)79.3%Not measuredOnly Claude Opus 5.5 measured
Terminal-Bench-Science (Vals AI)47.1%Not measuredOnly Claude Opus 5.5 measured
Vals Science Index58.7%Not measuredOnly Claude Opus 5.5 measured
Time Horizon Index (Vals AI)91.3%Not measuredOnly Claude Opus 5.5 measured
CUA-bench (Vals AI)14.0%Not measuredOnly Claude Opus 5.5 measured
Robo-bench (Vals AI)14.6%Not measuredOnly Claude Opus 5.5 measured
τ²-Bench TelecomNot measured97.7%Only Grok 4.3 measured
APEX-Agents73.5%Not measuredOnly Claude Opus 5.5 measured
Remote Labor Index21.3%Not measuredOnly Claude Opus 5.5 measured
SpireClimb3.3%Not measuredOnly Claude Opus 5.5 measured
Vending-Bench 2$9,235$35Claude Opus 5.5
LMArena Search12131166Claude Opus 5.5
Neither model has a result on the other 10 boards here
ReasoningLike-for-likePublic boards, shown as published, kept out of the index80
Reasoning benchmarks for Claude Opus 5.5 and Grok 4.3
BenchmarkClaude Opus 5.5Grok 4.3Leader
GPQA DiamondNot measured91.4%Only Grok 4.3 measured
LiveBench reasoning92.2%Not measuredOnly Claude Opus 5.5 measured
MysteryMechanism (Vals AI)49.5%Not measuredOnly Claude Opus 5.5 measured
MMMU Pro (Vals AI)Not measured83.1%Only Grok 4.3 measured
GPQA Diamond (Artificial Analysis run)Not measured90.1%Only Grok 4.3 measured
Humanity's Last Exam (Artificial Analysis run)61.4%37.2%Claude Opus 5.5
GPQA Diamond (Epoch AI run)90.6%88.8%Claude Opus 5.5
ARC-AGI98.5%Not measuredOnly Claude Opus 5.5 measured
ARC-AGI-293.3%Not measuredOnly Claude Opus 5.5 measured
Chess puzzles67.0%18.0%Claude Opus 5.5
Mystery game puzzles71.0%Not measuredOnly Claude Opus 5.5 measured
EBR-bench71.4%Not measuredOnly Claude Opus 5.5 measured
LMArena Text: hard prompts15361396Claude Opus 5.5
LMArena Text: expert15491384Claude Opus 5.5
LMArena Text: hard prompts in English15351402Claude Opus 5.5
LMArena Vision: diagrams13451241Claude Opus 5.5
LMArena Vision: homework13621241Claude Opus 5.5
Neither model has a result on the other 5 boards here
MathLike-for-likePublic boards, shown as published, kept out of the index60
Math benchmarks for Claude Opus 5.5 and Grok 4.3
BenchmarkClaude Opus 5.5Grok 4.3Leader
OTIS Mock AIME100.0%93.3%Claude Opus 5.5
FrontierMath, tiers 1 to 391.2%42.8%Claude Opus 5.5
FrontierMath, tier 495.0%14.6%Claude Opus 5.5
ProofBench100.0%11.0%Claude Opus 5.5
LMArena Text: math15181387Claude Opus 5.5
LMArena Text: mathematical work15161396Claude Opus 5.5
Neither model has a result on the other 7 boards here
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index60
Knowledge benchmarks for Claude Opus 5.5 and Grok 4.3
BenchmarkClaude Opus 5.5Grok 4.3Leader
MMLU ProNot measured85.8%Only Grok 4.3 measured
LegalBench (Vals AI)Not measured84.5%Only Grok 4.3 measured
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)Not measured70.8%Only Grok 4.3 measured
MortgageTax (Vals AI)Not measured48.3%Only Grok 4.3 measured
MedCode (Vals AI)49.8%38.1%Claude Opus 5.5
SimpleQA Verified72.2%33.2%Claude Opus 5.5
LMArena Text: science15241399Claude Opus 5.5
LMArena Text: medicine and healthcare15091384Claude Opus 5.5
LMArena Text: legal and government15181386Claude Opus 5.5
LMArena Text: business and finance14941381Claude Opus 5.5
FACTS Benchmark Suite65.3%Not measuredOnly Claude Opus 5.5 measured
Neither model has a result on the other 5 boards here
Web designLike-for-likePublic boards, shown as published, kept out of the index70
Web design benchmarks for Claude Opus 5.5 and Grok 4.3
BenchmarkClaude Opus 5.5Grok 4.3Leader
Design Arena: websites13351196Claude Opus 5.5
Design Arena: UI components13851190Claude Opus 5.5
Design Arena: game dev14611173Claude Opus 5.5
Design Arena: data viz13971179Claude Opus 5.5
Design Arena: 3D14761124Claude Opus 5.5
Design Arena: all code categories13901186Claude Opus 5.5
Design Arena: SVG13291080Claude Opus 5.5
Design Arena: ASCII artNot measured1125Only Grok 4.3 measured
LiveBench design86.9%Not measuredOnly Claude Opus 5.5 measured
GeneralLike-for-likePublic boards, shown as published, kept out of the index240
General benchmarks for Claude Opus 5.5 and Grok 4.3
BenchmarkClaude Opus 5.5Grok 4.3Leader
Vals Index70.2%Not measuredOnly Claude Opus 5.5 measured
LiveBench data analysis80.3%Not measuredOnly Claude Opus 5.5 measured
Public Benefits Bench (Vals AI)70.6%51.7%Claude Opus 5.5
SAGE (Vals AI)45.8%19.7%Claude Opus 5.5
MedScribe (Vals AI)91.4%74.4%Claude Opus 5.5
Vals Multimodal IndexNot measured43.3%Only Grok 4.3 measured
IFBenchNot measured83.3%Only Grok 4.3 measured
Long context reasoning (AA-LCR)84.7%75.0%Claude Opus 5.5
DTBench98.9%90.7%Claude Opus 5.5
LMCA68.2%38.3%Claude Opus 5.5
Furniture assembly83.3%Not measuredOnly Claude Opus 5.5 measured
LMArena Text15161397Claude Opus 5.5
LMArena Text: instruction following15371366Claude Opus 5.5
LMArena Text: creative writing15351380Claude Opus 5.5
LMArena Vision13211229Claude Opus 5.5
LMArena Text: English15191404Claude Opus 5.5
LMArena Text: non-English15071385Claude Opus 5.5
LMArena Text: Chinese15821422Claude Opus 5.5
LMArena Text: GermanNot measured1395Only Grok 4.3 measured
LMArena Text: Japanese15341379Claude Opus 5.5
LMArena Text: KoreanNot measured1354Only Grok 4.3 measured
LMArena Text: French14931411Claude Opus 5.5
LMArena Text: Spanish15081399Claude Opus 5.5
LMArena Text: Russian15171399Claude Opus 5.5
LMArena Text: PolishNot measured1398Only Grok 4.3 measured
LMArena Text: multi-turn15011406Claude Opus 5.5
LMArena Text: longer queries15321393Claude Opus 5.5
LMArena Text: writing and language15321385Claude Opus 5.5
LMArena Text: entertainment and media15151370Claude Opus 5.5
LMArena Vision: English13171235Claude Opus 5.5
LMArena Vision: ChineseNot measured1257Only Grok 4.3 measured
LMArena Vision: reading text13261235Claude Opus 5.5
LMArena Vision: humorNot measured1222Only Grok 4.3 measured
LMArena Vision: recognizing thingsNot measured1217Only Grok 4.3 measured
LMArena Vision: creative writing13201237Claude Opus 5.5
Neither model has a result on the other 11 boards here
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
Image generation benchmarks for Claude Opus 5.5 and Grok 4.3
BenchmarkClaude Opus 5.5Grok 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 Opus 5.5$0.014Fits in one request
Grok 4.3$0.0025Fits in one request

Grok 4.3 costs less

Repository review

50K input + 3K output tokens

Claude Opus 5.5$0.260Fits in one request
Grok 4.3$0.070Fits in one request

Grok 4.3 costs less

Agent loop

200K input + 10K output tokens

Claude Opus 5.5$1.00Fits 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 Opus 5.5 and Grok 4.3
SpecificationAnthropic Claude Opus 5.5SpaceXAI Grok 4.3
MakerAnthropicxAI
WeightsNo public weights listedNo public weights listed
ReleasedSeptember 22, 2026April 30, 2026
Context window1M1M
Input $/Mtok$4.00$1.25
Output $/Mtok$20.00$2.50
Coding index88.837.4
Independent measurements behind it53
Cost per solved taskNot computable$0.31
SourceOpenRouter listingOpenRouter listing

Questions

Is Claude Opus 5.5 better than Grok 4.3 for coding?

Pick Claude Opus 5.5 for coding: it scores 88.8 on the Vibe Coding Index against 37.4 for Grok 4.3. Pick Grok 4.3 for output tokens 8.0x cheaper ($2.50 vs $20.00 per million).

Which is cheaper, Claude Opus 5.5 or Grok 4.3?

Claude Opus 5.5 costs $4.00 per million input tokens and $20.00 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 Opus 5.5 or Grok 4.3?

Neither: both take 1M tokens.

How many benchmarks is the Claude Opus 5.5 vs Grok 4.3 comparison based on?

73 benchmarks have a result for both models as of October 22, 2026. Claude Opus 5.5's coding index rests on 5 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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