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Claude Opus 5.5 vs Grok 4.5

Updated October 21, 2026. 89 benchmarks have a result for both. Coding is ranked on the Vibe Coding Index; every other board is shown as published.

Replace Claude Opus 5.5 Replace Grok 4.5
Claude Opus 5.5Anthropic
Coding
92.2
Overall
57.6
Output $/M
$20.00
86
Grok 4.5xAI
Coding
75.5
Overall
38.8
Output $/M
$6.00
3
vs boards won of 89 shared

Decision reading

Pick Claude Opus 5.5 for coding: it scores 92.2 on the Vibe Coding Index against 75.5 for Grok 4.5.

Pick Grok 4.5 when output tokens cost 3.3x less, or when what matters is LiveBench research or LMArena Search, where it leads.

Model AClaude Opus 5.5Anthropic92.2/1002 independent benchmarksNo cost per solved taskModel BGrok 4.5xAI75.5/1002 independent benchmarks$0.62 per solved task
Shared results
89
Claude Opus 5.5 only
18
Grok 4.5 only
31
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 Opus 5.5 92.2 from 2 benchmarks, Grok 4.5 75.5 from 2 benchmarks.
Widest category
Math, 31.9 points apart on average over 6 shared benchmarks.
Widest single gap
Time Horizon Index (Vals AI): Claude Opus 5.5 91.3% against Grok 4.5 6.3%, 85.0 points apart on a 0 to 100 scale.
Output price
Claude Opus 5.5 $20.00 against Grok 4.5 $6.00 per million output tokens, 3.3x apart.
Context window
Claude Opus 5.5 takes 1M tokens, Grok 4.5 500K.

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 4.5Ties
Coding170
Intelligence20
Agentic work122
Reasoning101
Math60
Knowledge60
Web design80
General250
All shared boards863
CodingLike-for-likeFour of these boards feed the Vibe Coding Index170
Coding benchmarks for Claude Opus 5.5 and Grok 4.5
BenchmarkClaude Opus 5.5Grok 4.5Leader
LiveBench coding96.3%94.3%Claude Opus 5.5
LMArena WebDev18071553Claude Opus 5.5
AA Coding IndexNot measured72.4Only Grok 4.5 measured
LiveCodeBench (Vals AI)Not measured87.3%Only Grok 4.5 measured
SWE-bench Verified (Vals AI)Not measured86.6%Only Grok 4.5 measured
Terminal-Bench 4 (Vals AI)65.2%8.6%Claude Opus 5.5
Vibe Code Bench (Vals AI)90.3%69.0%Claude Opus 5.5
Code migration (Vals AI)66.7%36.6%Claude Opus 5.5
ProgramBench (Vals AI)18.5%0.0%Claude Opus 5.5
IOI (Vals AI)95.1%40.6%Claude Opus 5.5
Terminal-Bench 2.1 (Vals AI)87.6%67.8%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 measured66.0%Only Grok 4.5 measured
CyberBench (Vals AI)74.6%71.0%Claude Opus 5.5
SciCode66.9%55.0%Claude Opus 5.5
FrontierCode54.6%42.4%Claude Opus 5.5
FrontierSWE62.3%Not measuredOnly Claude Opus 5.5 measured
WeirdMLNot measured46.4%Only Grok 4.5 measured
MirrorCode77.4%Not measuredOnly Claude Opus 5.5 measured
ALE-Bench2147.41309.3Claude Opus 5.5
LMArena Text: coding15451474Claude Opus 5.5
LMArena Text: software and IT15381471Claude Opus 5.5
LMArena WebDev: React18551556Claude Opus 5.5
LMArena WebDev: HTML17531567Claude Opus 5.5
LMArena WebDev: from an image17531562Claude Opus 5.5
Neither model has a result on the other 12 boards here
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index20
Intelligence benchmarks for Claude Opus 5.5 and Grok 4.5
BenchmarkClaude Opus 5.5Grok 4.5Leader
AA Intelligence Index57.638.8Claude Opus 5.5
Epoch Capabilities Index168.8154.1Claude Opus 5.5
Agentic workLike-for-likePublic boards, shown as published, kept out of the index122
Agentic work benchmarks for Claude Opus 5.5 and Grok 4.5
BenchmarkClaude Opus 5.5Grok 4.5Leader
AA Agentic IndexNot measured41.2Only Grok 4.5 measured
Design Arena: agents building web apps13161217Claude Opus 5.5
Design Arena: agents building full-stack appsNot measured1249Only Grok 4.5 measured
Design Arena: agents building mobile apps13111221Claude Opus 5.5
Design Arena: agents building Android appsNot measured1242Only Grok 4.5 measured
Design Arena: agents building Godot gamesNot measured1229Only Grok 4.5 measured
Design Arena: agents building gamesNot measured1235Only Grok 4.5 measured
Design Arena: HTML slidesNot measured1204Only Grok 4.5 measured
Design Arena: PowerPoint slidesNot measured1232Only Grok 4.5 measured
Design Arena: spreadsheets1359Not measuredOnly Claude Opus 5.5 measured
LiveBench research85.0%85.9%Grok 4.5
LiveBench browser80.0%44.0%Claude Opus 5.5
LiveBench long agentic85.0%27.9%Claude Opus 5.5
SREBench (Vals AI)33.6%0.8%Claude Opus 5.5
Finance Agent (Vals AI)58.6%48.4%Claude Opus 5.5
Tax Agent Bench (Vals AI)45.6%24.9%Claude Opus 5.5
Legal Research Bench (Vals AI)50.5%38.0%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%52.9%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%6.3%Claude Opus 5.5
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
APEX-Agents73.5%56.2%Claude Opus 5.5
Remote Labor Index21.3%Not measuredOnly Claude Opus 5.5 measured
PostTrainBenchNot measured23.4%Only Grok 4.5 measured
SpireClimb3.3%Not measuredOnly Claude Opus 5.5 measured
Vending-Bench 2$9,235$3,887Claude Opus 5.5
LMArena Search12131216Grok 4.5
Neither model has a result on the other 8 boards here
ReasoningLike-for-likePublic boards, shown as published, kept out of the index101
Reasoning benchmarks for Claude Opus 5.5 and Grok 4.5
BenchmarkClaude Opus 5.5Grok 4.5Leader
GPQA DiamondNot measured92.9%Only Grok 4.5 measured
LiveBench reasoning92.2%87.2%Claude Opus 5.5
MysteryMechanism (Vals AI)49.5%Not measuredOnly Claude Opus 5.5 measured
MMMU Pro (Vals AI)Not measured61.8%Only Grok 4.5 measured
GPQA Diamond (Artificial Analysis run)Not measured93.1%Only Grok 4.5 measured
Humanity's Last Exam (Artificial Analysis run)61.4%42.7%Claude Opus 5.5
GPQA Diamond (Epoch AI run)90.6%93.4%Grok 4.5
ARC-AGI98.5%87.2%Claude Opus 5.5
ARC-AGI-293.3%52.6%Claude Opus 5.5
SimpleBenchNot measured70.0%Only Grok 4.5 measured
Chess puzzles67.0%35.0%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 prompts15361462Claude Opus 5.5
LMArena Text: expert15491465Claude Opus 5.5
LMArena Text: hard prompts in English15351464Claude Opus 5.5
LMArena Vision: diagrams13451304Claude Opus 5.5
LMArena Vision: homework13621295Claude Opus 5.5
Neither model has a result on the other 3 boards here
MathLike-for-likePublic boards, shown as published, kept out of the index60
Math benchmarks for Claude Opus 5.5 and Grok 4.5
BenchmarkClaude Opus 5.5Grok 4.5Leader
OTIS Mock AIME100.0%97.8%Claude Opus 5.5
FrontierMath, tiers 1 to 391.2%57.2%Claude Opus 5.5
FrontierMath, tier 495.0%24.4%Claude Opus 5.5
ProofBench100.0%31.0%Claude Opus 5.5
LMArena Text: math15181460Claude Opus 5.5
LMArena Text: mathematical work15161482Claude 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 4.5
BenchmarkClaude Opus 5.5Grok 4.5Leader
MMLU ProNot measured89.2%Only Grok 4.5 measured
LegalBench (Vals AI)Not measured86.0%Only Grok 4.5 measured
CorpFin (Vals AI)Not measured67.4%Only Grok 4.5 measured
TaxEval (Vals AI)Not measured71.7%Only Grok 4.5 measured
MortgageTax (Vals AI)Not measured61.8%Only Grok 4.5 measured
MedCode (Vals AI)49.8%43.3%Claude Opus 5.5
SimpleQA Verified72.2%48.3%Claude Opus 5.5
LMArena Text: science15241464Claude Opus 5.5
LMArena Text: medicine and healthcare15091440Claude Opus 5.5
LMArena Text: legal and government15181463Claude Opus 5.5
LMArena Text: business and finance14941441Claude Opus 5.5
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 Opus 5.5 and Grok 4.5
BenchmarkClaude Opus 5.5Grok 4.5Leader
Design Arena: websites13351281Claude Opus 5.5
Design Arena: UI components13901279Claude Opus 5.5
Design Arena: game dev14571263Claude Opus 5.5
Design Arena: data viz13971267Claude Opus 5.5
Design Arena: 3D14771257Claude Opus 5.5
Design Arena: all code categories13901276Claude Opus 5.5
Design Arena: SVG13321215Claude Opus 5.5
Design Arena: ASCII artNot measured1257Only Grok 4.5 measured
LiveBench design86.9%78.1%Claude Opus 5.5
GeneralLike-for-likePublic boards, shown as published, kept out of the index250
General benchmarks for Claude Opus 5.5 and Grok 4.5
BenchmarkClaude Opus 5.5Grok 4.5Leader
Vals Index70.2%Not measuredOnly Claude Opus 5.5 measured
LiveBench data analysis80.3%73.0%Claude Opus 5.5
Public Benefits Bench (Vals AI)70.6%Not measuredOnly Claude Opus 5.5 measured
SAGE (Vals AI)45.8%35.0%Claude Opus 5.5
MedScribe (Vals AI)91.4%86.9%Claude Opus 5.5
Vals Multimodal IndexNot measured63.4%Only Grok 4.5 measured
Long context reasoning (AA-LCR)84.7%79.3%Claude Opus 5.5
DTBench98.9%96.5%Claude Opus 5.5
LMCA68.2%45.2%Claude Opus 5.5
Surface Evolver BenchNot measured74.4%Only Grok 4.5 measured
Furniture assembly83.3%22.5%Claude Opus 5.5
LMArena Text15161448Claude Opus 5.5
LMArena Text: instruction following15371445Claude Opus 5.5
LMArena Text: creative writing15351442Claude Opus 5.5
LMArena Vision13211287Claude Opus 5.5
LMArena Text: English15191453Claude Opus 5.5
LMArena Text: non-English15071440Claude Opus 5.5
LMArena Text: Chinese15821495Claude Opus 5.5
LMArena Text: GermanNot measured1448Only Grok 4.5 measured
LMArena Text: Japanese15341430Claude Opus 5.5
LMArena Text: KoreanNot measured1406Only Grok 4.5 measured
LMArena Text: French14931457Claude Opus 5.5
LMArena Text: Spanish15081451Claude Opus 5.5
LMArena Text: Russian15171449Claude Opus 5.5
LMArena Text: PolishNot measured1432Only Grok 4.5 measured
LMArena Text: multi-turn15011456Claude Opus 5.5
LMArena Text: longer queries15321462Claude Opus 5.5
LMArena Text: writing and language15321445Claude Opus 5.5
LMArena Text: entertainment and media15151434Claude Opus 5.5
LMArena Vision: English13171285Claude Opus 5.5
LMArena Vision: ChineseNot measured1345Only Grok 4.5 measured
LMArena Vision: reading text13261293Claude Opus 5.5
LMArena Vision: humorNot measured1276Only Grok 4.5 measured
LMArena Vision: creative writing13201293Claude Opus 5.5
LMArena DocumentNot measured1452Only Grok 4.5 measured
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 4.5
BenchmarkClaude Opus 5.5Grok 4.5Leader
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 4.5$0.0050Fits in one request

Grok 4.5 costs less

Repository review

50K input + 3K output tokens

Claude Opus 5.5$0.260Fits in one request
Grok 4.5$0.118Fits in one request

Grok 4.5 costs less

Agent loop

200K input + 10K output tokens

Claude Opus 5.5$1.00Fits in one request
Grok 4.5$0.460Fits in one request

Grok 4.5 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 4.5
SpecificationAnthropic Claude Opus 5.5SpaceXAI Grok 4.5
MakerAnthropicxAI
WeightsNo public weights listedNo public weights listed
ReleasedSeptember 22, 2026July 8, 2026
Context window1M500K
Input $/Mtok$4.00$2.00
Output $/Mtok$20.00$6.00
Coding index92.275.5
Independent measurements behind it22
Cost per solved taskNot computable$0.62
SourceOpenRouter listingOpenRouter listing

Questions

Is Claude Opus 5.5 better than Grok 4.5 for coding?

Pick Claude Opus 5.5 for coding: it scores 92.2 on the Vibe Coding Index against 75.5 for Grok 4.5. Pick Grok 4.5 when output tokens cost 3.3x less, or when what matters is LiveBench research or LMArena Search, where it leads.

Which is cheaper, Claude Opus 5.5 or Grok 4.5?

Claude Opus 5.5 costs $4.00 per million input tokens and $20.00 per million output tokens; Grok 4.5 costs $2.00 and $6.00. Cost per solved task is known for Grok 4.5 only.

Which has the bigger context window, Claude Opus 5.5 or Grok 4.5?

Claude Opus 5.5, with 1M tokens against 500K.

How many benchmarks is the Claude Opus 5.5 vs Grok 4.5 comparison based on?

89 benchmarks have a result for both models as of October 21, 2026. Claude Opus 5.5's coding index rests on 2 independent benchmarks and Grok 4.5's on 2. Where only one model has a result, the page says so instead of naming a winner.

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