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Gemini 4 Argon vs GPT-5.6 Luna

Gemini 4 Argon leads GPT-5.6 Luna on coding, 81.0 to 58.0 on the Vibe Coding Index, and GPT-5.6 Luna costs 8.3x less per output token ($1.20 vs $10.00 per million). Updated October 22, 2026; 84 benchmarks have a result for both.

Replace Gemini 4 Argon Replace GPT-5.6 Luna
Gemini 4 ArgonGoogle
Coding
81.0
Overall
84.0
Output $/M
$10.00
80
GPT-5.6 LunaOpenAI
Coding
58.0
Overall
61.6
Output $/M
$1.20
4
vs boards won of 84 shared

Gemini 4 Argon or GPT-5.6 Luna: which to pick

Pick Gemini 4 Argon for coding: it scores 81.0 on the Vibe Coding Index against 58.0 for GPT-5.6 Luna, though on 5 benchmarks against 6.

Pick GPT-5.6 Luna for output tokens 8.3x cheaper ($1.20 vs $10.00 per million) and a larger context window (1.05M against 1.05M tokens).

Model AGemini 4 ArgonGoogle81.0/1005 independent benchmarksNo cost per solved taskModel BGPT-5.6 LunaOpenAI58.0/1006 independent benchmarks$0.04 per solved task
Shared results
84
Gemini 4 Argon only
10
GPT-5.6 Luna only
35
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
Gemini 4 Argon 81.0 from 5 benchmarks, GPT-5.6 Luna 58.0 from 6 benchmarks.
Widest category
Agentic work, 29.5 points apart on average over 13 shared benchmarks.
Widest single gap
Terminal-Bench 4 (Vals AI): Gemini 4 Argon 57.6% against GPT-5.6 Luna 11.6%, 61.3 points apart on a 0 to 100 scale.
Output price
Gemini 4 Argon $10.00 against GPT-5.6 Luna $1.20 per million output tokens, 8.3x apart.
Context window
Gemini 4 Argon takes 1.05M tokens, GPT-5.6 Luna 1.05M.

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
CategoryGemini 4 ArgonBarsGPT-5.6 LunaTies
Coding162
Intelligence20
Agentic work130
Reasoning110
Math60
Knowledge70
Web design61
General191
All shared boards804
CodingLike-for-likeSix of these boards feed the Vibe Coding Index162
Coding benchmarks for Gemini 4 Argon and GPT-5.6 Luna
BenchmarkGemini 4 ArgonGPT-5.6 LunaLeader
LiveBench coding89.7%73.6%Gemini 4 Argon
LMArena WebDev16781518Gemini 4 Argon
AA Coding IndexNot measured71.4Only GPT-5.6 Luna measured
SWE-bench Verified (Vals AI)Not measured93.0%Only GPT-5.6 Luna measured
Terminal-Bench 4 (Vals AI)57.6%11.6%Gemini 4 Argon
Vibe Code Bench (Vals AI)91.9%77.1%Gemini 4 Argon
Code migration (Vals AI)68.2%44.5%Gemini 4 Argon
ProgramBench (Vals AI)2.5%0.0%Gemini 4 Argon
IOI (Vals AI)100.0%61.8%Gemini 4 Argon
Terminal-Bench 2.1 (Vals AI)57.7%79.0%GPT-5.6 Luna
SWE-bench Multimodal (Vals AI)56.0%Not measuredOnly Gemini 4 Argon measured
Vibe Code Bench 1-100 (Vals AI)21.2%22.6%GPT-5.6 Luna
SkillsBench (Vals AI)Not measured60.5%Only GPT-5.6 Luna measured
CyberBench (Vals AI)77.9%73.6%Gemini 4 Argon
SciCode61.8%53.6%Gemini 4 Argon
FrontierCode47.5%39.8%Gemini 4 Argon
FrontierSWE55.0%Not measuredOnly Gemini 4 Argon measured
WeirdMLNot measured60.9%Only GPT-5.6 Luna measured
MirrorCode58.9%Not measuredOnly Gemini 4 Argon measured
ALE-Bench2100.11667.4Gemini 4 Argon
LMArena Text: coding15461466Gemini 4 Argon
LMArena Text: software and IT15561463Gemini 4 Argon
LMArena WebDev: React16921508Gemini 4 Argon
LMArena WebDev: HTML16431520Gemini 4 Argon
LMArena WebDev: from an imageNot measured1517Only GPT-5.6 Luna measured
SciCode12.3%6.2%Gemini 4 Argon
Neither model has a result on the other 13 boards here
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index20
Intelligence benchmarks for Gemini 4 Argon and GPT-5.6 Luna
BenchmarkGemini 4 ArgonGPT-5.6 LunaLeader
AA Intelligence Index52.637.3Gemini 4 Argon
Epoch Capabilities Index166.4156.5Gemini 4 Argon
Agentic workLike-for-likePublic boards, shown as published, kept out of the index130
Agentic work benchmarks for Gemini 4 Argon and GPT-5.6 Luna
BenchmarkGemini 4 ArgonGPT-5.6 LunaLeader
AA Agentic IndexNot measured42.1Only GPT-5.6 Luna measured
Design Arena: spreadsheets1157Not measuredOnly Gemini 4 Argon measured
LiveBench research83.1%51.0%Gemini 4 Argon
LiveBench browser92.0%68.0%Gemini 4 Argon
LiveBench long agentic69.9%30.4%Gemini 4 Argon
SREBench (Vals AI)44.3%1.5%Gemini 4 Argon
Finance Agent (Vals AI)65.4%55.0%Gemini 4 Argon
Tax Agent Bench (Vals AI)44.6%24.8%Gemini 4 Argon
Legal Research Bench (Vals AI)54.8%36.5%Gemini 4 Argon
Harvey's Legal Agent Benchmark (Vals AI)27.1%Not measuredOnly Gemini 4 Argon measured
Excel Modeling Benchmark (Vals AI)75.2%67.1%Gemini 4 Argon
BioMysteryBench (Vals AI)76.3%61.5%Gemini 4 Argon
Terminal-Bench-Science (Vals AI)44.3%0.0%Gemini 4 Argon
Vals Science Index55.4%25.3%Gemini 4 Argon
Time Horizon Index (Vals AI)52.5%Not measuredOnly Gemini 4 Argon measured
CUA-bench (Vals AI)4.8%Not measuredOnly Gemini 4 Argon measured
Robo-bench (Vals AI)0.8%Not measuredOnly Gemini 4 Argon measured
APEX-Agents82.4%43.0%Gemini 4 Argon
BALROGNot measured45.6%Only GPT-5.6 Luna measured
Vending-Bench 2$13,718$4,095Gemini 4 Argon
Neither model has a result on the other 21 boards here
ReasoningLike-for-likePublic boards, shown as published, kept out of the index110
Reasoning benchmarks for Gemini 4 Argon and GPT-5.6 Luna
BenchmarkGemini 4 ArgonGPT-5.6 LunaLeader
GPQA DiamondNot measured91.7%Only GPT-5.6 Luna measured
LiveBench reasoning95.1%85.6%Gemini 4 Argon
MysteryMechanism (Vals AI)45.5%14.4%Gemini 4 Argon
MMMU Pro (Vals AI)Not measured85.0%Only GPT-5.6 Luna measured
GPQA Diamond (Artificial Analysis run)Not measured91.1%Only GPT-5.6 Luna measured
Humanity's Last Exam (Artificial Analysis run)57.1%39.5%Gemini 4 Argon
GPQA Diamond (Epoch AI run)96.4%91.6%Gemini 4 Argon
ARC-AGI98.5%88.0%Gemini 4 Argon
ARC-AGI-291.3%59.5%Gemini 4 Argon
SimpleBenchNot measured46.8%Only GPT-5.6 Luna measured
Chess puzzles59.0%43.0%Gemini 4 Argon
Mystery game puzzles64.0%21.0%Gemini 4 Argon
EBR-bench64.8%Not measuredOnly Gemini 4 Argon measured
LMArena Text: hard prompts15461451Gemini 4 Argon
LMArena Text: expert15501478Gemini 4 Argon
LMArena Text: hard prompts in English15481460Gemini 4 Argon
LMArena Vision: diagramsNot measured1273Only GPT-5.6 Luna measured
LMArena Vision: homeworkNot measured1282Only GPT-5.6 Luna measured
Kagi LLM BenchmarkNot measured49.1%Only 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 index60
Math benchmarks for Gemini 4 Argon and GPT-5.6 Luna
BenchmarkGemini 4 ArgonGPT-5.6 LunaLeader
OTIS Mock AIME100.0%98.3%Gemini 4 Argon
FrontierMath, tiers 1 to 386.0%82.1%Gemini 4 Argon
FrontierMath, tier 478.0%61.0%Gemini 4 Argon
ProofBench99.0%60.0%Gemini 4 Argon
LMArena Text: math15361459Gemini 4 Argon
LMArena Text: mathematical work15571470Gemini 4 Argon
Neither model has a result on the other 7 boards here
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index70
Knowledge benchmarks for Gemini 4 Argon and GPT-5.6 Luna
BenchmarkGemini 4 ArgonGPT-5.6 LunaLeader
MMLU ProNot measured86.0%Only GPT-5.6 Luna measured
LegalBench (Vals AI)88.3%84.0%Gemini 4 Argon
CorpFin (Vals AI)Not measured64.2%Only GPT-5.6 Luna measured
TaxEval (Vals AI)Not measured76.2%Only GPT-5.6 Luna measured
MortgageTax (Vals AI)Not measured67.3%Only GPT-5.6 Luna measured
MedCode (Vals AI)58.8%42.4%Gemini 4 Argon
SimpleQA Verified76.0%41.0%Gemini 4 Argon
LMArena Text: science15481433Gemini 4 Argon
LMArena Text: medicine and healthcare15551399Gemini 4 Argon
LMArena Text: legal and government15481446Gemini 4 Argon
LMArena Text: business and finance15251439Gemini 4 Argon
FACTS Benchmark SuiteNot measured35.0%Only 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 index61
Web design benchmarks for Gemini 4 Argon and GPT-5.6 Luna
BenchmarkGemini 4 ArgonGPT-5.6 LunaLeader
Design Arena: websites13151255Gemini 4 Argon
Design Arena: UI components13331248Gemini 4 Argon
Design Arena: game dev13771194Gemini 4 Argon
Design Arena: data viz13321211Gemini 4 Argon
Design Arena: 3D13881121Gemini 4 Argon
Design Arena: all code categories13291231Gemini 4 Argon
Design Arena: SVGNot measured1194Only GPT-5.6 Luna measured
Design Arena: ASCII artNot measured1142Only GPT-5.6 Luna measured
LiveBench design73.7%76.0%GPT-5.6 Luna
GeneralLike-for-likePublic boards, shown as published, kept out of the index191
General benchmarks for Gemini 4 Argon and GPT-5.6 Luna
BenchmarkGemini 4 ArgonGPT-5.6 LunaLeader
Vals Index69.2%Not measuredOnly Gemini 4 Argon measured
LiveBench data analysis85.2%78.0%Gemini 4 Argon
Public Benefits Bench (Vals AI)69.8%61.2%Gemini 4 Argon
SAGE (Vals AI)53.6%44.2%Gemini 4 Argon
MedScribe (Vals AI)87.4%84.4%Gemini 4 Argon
Vals Multimodal IndexNot measured69.1%Only GPT-5.6 Luna measured
Long context reasoning (AA-LCR)79.7%83.7%GPT-5.6 Luna
DTBench97.6%89.1%Gemini 4 Argon
LMCA63.7%48.5%Gemini 4 Argon
Surface Evolver BenchNot measured61.9%Only GPT-5.6 Luna measured
Furniture assembly72.5%42.5%Gemini 4 Argon
LMArena Text15321431Gemini 4 Argon
LMArena Text: instruction following15341437Gemini 4 Argon
LMArena Text: creative writing15271396Gemini 4 Argon
LMArena VisionNot measured1257Only GPT-5.6 Luna measured
LMArena Text: English15381441Gemini 4 Argon
LMArena Text: non-English15221417Gemini 4 Argon
LMArena Text: Chinese16111470Gemini 4 Argon
LMArena Text: GermanNot measured1455Only GPT-5.6 Luna measured
LMArena Text: JapaneseNot measured1415Only GPT-5.6 Luna measured
LMArena Text: KoreanNot measured1415Only GPT-5.6 Luna measured
LMArena Text: FrenchNot measured1458Only GPT-5.6 Luna measured
LMArena Text: Spanish15031446Gemini 4 Argon
LMArena Text: Russian15341427Gemini 4 Argon
LMArena Text: PolishNot measured1405Only GPT-5.6 Luna measured
LMArena Text: multi-turn15561434Gemini 4 Argon
LMArena Text: longer queries15471436Gemini 4 Argon
LMArena Text: writing and language15291419Gemini 4 Argon
LMArena Text: entertainment and media15271402Gemini 4 Argon
LMArena Vision: EnglishNot measured1263Only GPT-5.6 Luna measured
LMArena Vision: ChineseNot measured1294Only GPT-5.6 Luna measured
LMArena Vision: reading textNot measured1264Only GPT-5.6 Luna measured
LMArena Vision: humorNot measured1190Only GPT-5.6 Luna measured
LMArena Vision: creative writingNot measured1257Only GPT-5.6 Luna measured
LMArena DocumentNot measured1457Only GPT-5.6 Luna 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 Gemini 4 Argon and GPT-5.6 Luna
BenchmarkGemini 4 ArgonGPT-5.6 LunaLeader
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

Gemini 4 Argon$0.0070Fits in one request
GPT-5.6 Luna$0.0008Fits in one request

GPT-5.6 Luna costs less

Repository review

50K input + 3K output tokens

Gemini 4 Argon$0.130Fits in one request
GPT-5.6 Luna$0.014Fits in one request

GPT-5.6 Luna costs less

Agent loop

200K input + 10K output tokens

Gemini 4 Argon$0.500Fits in one request
GPT-5.6 Luna$0.052Fits 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 Gemini 4 Argon and GPT-5.6 Luna
SpecificationGoogle Gemini 4 ArgonOpenAI GPT-5.6 Luna
MakerGoogleOpenAI
WeightsNo public weights listedNo public weights listed
ReleasedOctober 13, 2026July 9, 2026
Context window1.05M1.05M
Input $/Mtok$2.00$0.20
Output $/Mtok$10.00$1.20
Coding index81.058.0
Independent measurements behind it56
Cost per solved taskNot computable$0.04
SourceOpenRouter listingOpenRouter listing

Questions

Is Gemini 4 Argon better than GPT-5.6 Luna for coding?

Pick Gemini 4 Argon for coding: it scores 81.0 on the Vibe Coding Index against 58.0 for GPT-5.6 Luna, though on 5 benchmarks against 6. Pick GPT-5.6 Luna for output tokens 8.3x cheaper ($1.20 vs $10.00 per million) and a larger context window (1.05M against 1.05M tokens).

Which is cheaper, Gemini 4 Argon or GPT-5.6 Luna?

Gemini 4 Argon costs $2.00 per million input tokens and $10.00 per million output tokens; GPT-5.6 Luna costs $0.20 and $1.20. Cost per solved task is known for GPT-5.6 Luna only.

Which has the bigger context window, Gemini 4 Argon or GPT-5.6 Luna?

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

How many benchmarks is the Gemini 4 Argon vs GPT-5.6 Luna comparison based on?

84 benchmarks have a result for both models as of October 22, 2026. Gemini 4 Argon's coding index rests on 5 independent benchmarks and GPT-5.6 Luna's on 6. Where only one model has a result, the page says so instead of naming a winner.

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