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GPT-5.6 Luna vs Grok 4.6

Grok 4.6 leads GPT-5.6 Luna on coding, 65.7 to 58.0 on the Vibe Coding Index, and GPT-5.6 Luna costs 5.0x less per output token ($1.20 vs $6.00 per million). Updated October 22, 2026; 111 benchmarks have a result for both.

Replace GPT-5.6 Luna Replace Grok 4.6
GPT-5.6 LunaOpenAI
Coding
58.0
Overall
61.6
Output $/M
$1.20
43
Grok 4.6xAI
Coding
65.7
Overall
67.4
Output $/M
$6.00
68
vs boards won of 111 shared

GPT-5.6 Luna or Grok 4.6: which to pick

Pick Grok 4.6 for coding: it scores 65.7 on the Vibe Coding Index against 58.0 for GPT-5.6 Luna.

Pick GPT-5.6 Luna for output tokens 5.0x cheaper ($1.20 vs $6.00 per million) and a lower cost per solved task ($0.04 against $0.82).

Model AGPT-5.6 LunaOpenAI58.0/1006 independent benchmarks$0.04 per solved taskModel BGrok 4.6xAI65.7/1006 independent benchmarks$0.82 per solved task
Shared results
111
GPT-5.6 Luna only
8
Grok 4.6 only
12
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
GPT-5.6 Luna 58.0 from 6 benchmarks, Grok 4.6 65.7 from 6 benchmarks.
Widest category
Agentic work, 13.3 points apart on average over 13 shared benchmarks.
Widest single gap
LiveBench research: GPT-5.6 Luna 51.0% against Grok 4.6 84.5%, 33.5 points apart on a 0 to 100 scale.
Output price
GPT-5.6 Luna $1.20 against Grok 4.6 $6.00 per million output tokens, 5.0x apart.
Context window
GPT-5.6 Luna takes 1.05M tokens, Grok 4.6 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
CategoryGPT-5.6 LunaBarsGrok 4.6Ties
Coding913
Intelligence02
Agentic work310
Reasoning511
Math51
Knowledge47
Web design09
General1715
All shared boards4368
CodingLike-for-likeSix of these boards feed the Vibe Coding Index913
Coding benchmarks for GPT-5.6 Luna and Grok 4.6
BenchmarkGPT-5.6 LunaGrok 4.6Leader
LiveBench coding73.6%89.1%Grok 4.6
LMArena WebDev15181617Grok 4.6
AA Coding Index71.476.8Grok 4.6
LiveCodeBench (Vals AI)Not measured88.2%Only Grok 4.6 measured
SWE-bench Verified (Vals AI)93.0%95.6%Grok 4.6
Terminal-Bench 4 (Vals AI)11.6%17.2%Grok 4.6
Vibe Code Bench (Vals AI)77.1%76.2%GPT-5.6 Luna
Code migration (Vals AI)44.5%44.6%Grok 4.6
ProgramBench (Vals AI)0.0%1.0%Grok 4.6
IOI (Vals AI)61.8%47.6%GPT-5.6 Luna
Terminal-Bench 2.1 (Vals AI)79.0%78.3%GPT-5.6 Luna
Vibe Code Bench 1-100 (Vals AI)22.6%14.8%GPT-5.6 Luna
SkillsBench (Vals AI)60.5%55.8%GPT-5.6 Luna
CyberBench (Vals AI)73.6%67.7%GPT-5.6 Luna
SciCode53.6%56.5%Grok 4.6
FrontierCode39.8%48.0%Grok 4.6
FrontierSWENot measured25.3%Only Grok 4.6 measured
WeirdML60.9%67.3%Grok 4.6
ALE-Bench1667.41508.1GPT-5.6 Luna
LMArena Text: coding14661466GPT-5.6 Luna
LMArena Text: software and IT14631457GPT-5.6 Luna
LMArena WebDev: React15081631Grok 4.6
LMArena WebDev: HTML15201597Grok 4.6
LMArena WebDev: from an image15171603Grok 4.6
SciCode6.2%Not measuredOnly GPT-5.6 Luna measured
Neither model has a result on the other 14 boards here
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index02
Intelligence benchmarks for GPT-5.6 Luna and Grok 4.6
BenchmarkGPT-5.6 LunaGrok 4.6Leader
AA Intelligence Index37.344.3Grok 4.6
Epoch Capabilities Index156.5156.6Grok 4.6
Agentic workLike-for-likePublic boards, shown as published, kept out of the index310
Agentic work benchmarks for GPT-5.6 Luna and Grok 4.6
BenchmarkGPT-5.6 LunaGrok 4.6Leader
AA Agentic Index42.153.0Grok 4.6
Design Arena: agents building web appsNot measured1248Only Grok 4.6 measured
Design Arena: agents building full-stack appsNot measured1264Only Grok 4.6 measured
Design Arena: agents building mobile appsNot measured1234Only Grok 4.6 measured
Design Arena: agents building Android appsNot measured1291Only Grok 4.6 measured
Design Arena: agents building Godot gamesNot measured1276Only Grok 4.6 measured
Design Arena: agents building gamesNot measured1210Only Grok 4.6 measured
Design Arena: HTML slidesNot measured1200Only Grok 4.6 measured
Design Arena: PowerPoint slidesNot measured1216Only Grok 4.6 measured
LiveBench research51.0%84.5%Grok 4.6
LiveBench browser68.0%64.0%GPT-5.6 Luna
LiveBench long agentic30.4%40.7%Grok 4.6
SREBench (Vals AI)1.5%Not measuredOnly GPT-5.6 Luna measured
Finance Agent (Vals AI)55.0%53.7%GPT-5.6 Luna
Tax Agent Bench (Vals AI)24.8%33.1%Grok 4.6
Legal Research Bench (Vals AI)36.5%48.1%Grok 4.6
Excel Modeling Benchmark (Vals AI)67.1%62.7%GPT-5.6 Luna
BioMysteryBench (Vals AI)61.5%72.2%Grok 4.6
Terminal-Bench-Science (Vals AI)0.0%11.4%Grok 4.6
Vals Science Index25.3%38.1%Grok 4.6
Time Horizon Index (Vals AI)Not measured5.8%Only Grok 4.6 measured
APEX-Agents43.0%65.3%Grok 4.6
BALROG45.6%Not measuredOnly GPT-5.6 Luna measured
Vending-Bench 2$4,095$9,047Grok 4.6
Neither model has a result on the other 17 boards here
ReasoningLike-for-likePublic boards, shown as published, kept out of the index511
Reasoning benchmarks for GPT-5.6 Luna and Grok 4.6
BenchmarkGPT-5.6 LunaGrok 4.6Leader
GPQA Diamond91.7%94.7%Grok 4.6
LiveBench reasoning85.6%91.2%Grok 4.6
MysteryMechanism (Vals AI)14.4%30.6%Grok 4.6
MMMU Pro (Vals AI)85.0%Not measuredOnly GPT-5.6 Luna measured
GPQA Diamond (Artificial Analysis run)91.1%94.9%Grok 4.6
Humanity's Last Exam (Artificial Analysis run)39.5%44.1%Grok 4.6
GPQA Diamond (Epoch AI run)91.6%94.0%Grok 4.6
ARC-AGI88.0%87.5%GPT-5.6 Luna
ARC-AGI-259.5%67.1%Grok 4.6
SimpleBench46.8%75.9%Grok 4.6
Chess puzzles43.0%33.0%GPT-5.6 Luna
Mystery game puzzles21.0%34.0%Grok 4.6
EBR-benchNot measured30.5%Only Grok 4.6 measured
LMArena Text: hard prompts14511448GPT-5.6 Luna
LMArena Text: expert14781469GPT-5.6 Luna
LMArena Text: hard prompts in English14601445GPT-5.6 Luna
LMArena Vision: diagrams12731285Grok 4.6
LMArena Vision: homework12821283Grok 4.6
Kagi LLM Benchmark49.1%Not measuredOnly GPT-5.6 Luna measured
Neither model has a result on the other 3 boards here
MathLike-for-likePublic boards, shown as published, kept out of the index51
Math benchmarks for GPT-5.6 Luna and Grok 4.6
BenchmarkGPT-5.6 LunaGrok 4.6Leader
OTIS Mock AIME98.3%99.2%Grok 4.6
FrontierMath, tiers 1 to 382.1%66.0%GPT-5.6 Luna
FrontierMath, tier 461.0%31.7%GPT-5.6 Luna
ProofBench60.0%51.0%GPT-5.6 Luna
LMArena Text: math14591417GPT-5.6 Luna
LMArena Text: mathematical work14701464GPT-5.6 Luna
Neither model has a result on the other 7 boards here
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index47
Knowledge benchmarks for GPT-5.6 Luna and Grok 4.6
BenchmarkGPT-5.6 LunaGrok 4.6Leader
MMLU Pro86.0%89.4%Grok 4.6
LegalBench (Vals AI)84.0%86.3%Grok 4.6
CorpFin (Vals AI)64.2%66.2%Grok 4.6
TaxEval (Vals AI)76.2%71.1%GPT-5.6 Luna
MortgageTax (Vals AI)67.3%64.2%GPT-5.6 Luna
MedCode (Vals AI)42.4%44.7%Grok 4.6
SimpleQA Verified41.0%49.3%Grok 4.6
LMArena Text: science14331437Grok 4.6
LMArena Text: medicine and healthcare13991420Grok 4.6
LMArena Text: legal and government14461429GPT-5.6 Luna
LMArena Text: business and finance14391416GPT-5.6 Luna
FACTS Benchmark Suite35.0%Not measuredOnly GPT-5.6 Luna measured
Neither model has a result on the other 6 boards here
Web designLike-for-likePublic boards, shown as published, kept out of the index09
Web design benchmarks for GPT-5.6 Luna and Grok 4.6
BenchmarkGPT-5.6 LunaGrok 4.6Leader
Design Arena: websites12551289Grok 4.6
Design Arena: UI components12481293Grok 4.6
Design Arena: game dev11951295Grok 4.6
Design Arena: data viz12121282Grok 4.6
Design Arena: 3D11211275Grok 4.6
Design Arena: all code categories12301292Grok 4.6
Design Arena: SVG11931238Grok 4.6
Design Arena: ASCII art11421279Grok 4.6
LiveBench design76.0%79.8%Grok 4.6
GeneralLike-for-likePublic boards, shown as published, kept out of the index1715
General benchmarks for GPT-5.6 Luna and Grok 4.6
BenchmarkGPT-5.6 LunaGrok 4.6Leader
LiveBench data analysis78.0%75.3%GPT-5.6 Luna
Public Benefits Bench (Vals AI)61.2%66.8%Grok 4.6
SAGE (Vals AI)44.2%28.9%GPT-5.6 Luna
MedScribe (Vals AI)84.4%86.5%Grok 4.6
Vals Multimodal Index69.1%Not measuredOnly GPT-5.6 Luna measured
Long context reasoning (AA-LCR)83.7%81.0%GPT-5.6 Luna
DTBench89.1%97.3%Grok 4.6
LMCA48.5%48.5%GPT-5.6 Luna
Surface Evolver Bench61.9%Not measuredOnly GPT-5.6 Luna measured
Furniture assembly42.5%40.0%GPT-5.6 Luna
LMArena Text14311429GPT-5.6 Luna
LMArena Text: instruction following14371431GPT-5.6 Luna
LMArena Text: creative writing13961426Grok 4.6
LMArena Vision12571263Grok 4.6
LMArena Text: English14411433GPT-5.6 Luna
LMArena Text: non-English14171420Grok 4.6
LMArena Text: Chinese14701476Grok 4.6
LMArena Text: German14551426GPT-5.6 Luna
LMArena Text: Japanese14151378GPT-5.6 Luna
LMArena Text: Korean14151391GPT-5.6 Luna
LMArena Text: French14581455GPT-5.6 Luna
LMArena Text: Spanish14461414GPT-5.6 Luna
LMArena Text: Russian14271421GPT-5.6 Luna
LMArena Text: Polish14051430Grok 4.6
LMArena Text: multi-turn14341425GPT-5.6 Luna
LMArena Text: longer queries14361456Grok 4.6
LMArena Text: writing and language14191429Grok 4.6
LMArena Text: entertainment and media14021421Grok 4.6
LMArena Vision: English12631270Grok 4.6
LMArena Vision: Chinese12941289GPT-5.6 Luna
LMArena Vision: reading text12641272Grok 4.6
LMArena Vision: humor11901270Grok 4.6
LMArena Vision: creative writing12571262Grok 4.6
LMArena Document14571452GPT-5.6 Luna
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 GPT-5.6 Luna and Grok 4.6
BenchmarkGPT-5.6 LunaGrok 4.6Leader
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

GPT-5.6 Luna$0.0008Fits in one request
Grok 4.6$0.0050Fits in one request

GPT-5.6 Luna costs less

Repository review

50K input + 3K output tokens

GPT-5.6 Luna$0.014Fits in one request
Grok 4.6$0.118Fits in one request

GPT-5.6 Luna costs less

Agent loop

200K input + 10K output tokens

GPT-5.6 Luna$0.052Fits in one request
Grok 4.6$0.460Fits in one request

GPT-5.6 Luna 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 GPT-5.6 Luna and Grok 4.6
SpecificationOpenAI GPT-5.6 LunaSpaceXAI Grok 4.6
MakerOpenAIxAI
WeightsNo public weights listedNo public weights listed
ReleasedJuly 9, 2026August 12, 2026
Context window1.05M500K
Input $/Mtok$0.20$2.00
Output $/Mtok$1.20$6.00
Coding index58.065.7
Independent measurements behind it66
Cost per solved task$0.04$0.82
SourceOpenRouter listingOpenRouter listing

Questions

Is GPT-5.6 Luna better than Grok 4.6 for coding?

Pick Grok 4.6 for coding: it scores 65.7 on the Vibe Coding Index against 58.0 for GPT-5.6 Luna. Pick GPT-5.6 Luna for output tokens 5.0x cheaper ($1.20 vs $6.00 per million) and a lower cost per solved task ($0.04 against $0.82).

Which is cheaper, GPT-5.6 Luna or Grok 4.6?

GPT-5.6 Luna costs $0.20 per million input tokens and $1.20 per million output tokens; Grok 4.6 costs $2.00 and $6.00. Per solved SWE-bench Verified task, GPT-5.6 Luna costs $0.04 and Grok 4.6 $0.82.

Which has the bigger context window, GPT-5.6 Luna or Grok 4.6?

GPT-5.6 Luna, with 1.05M tokens against 500K.

How many benchmarks is the GPT-5.6 Luna vs Grok 4.6 comparison based on?

111 benchmarks have a result for both models as of October 22, 2026. GPT-5.6 Luna's coding index rests on 6 independent benchmarks and Grok 4.6's on 6. Where only one model has a result, the page says so instead of naming a winner.

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