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Gemini 3.1 Flash Lite Preview vs GPT-5.6 Luna

Updated October 21, 2026. 72 benchmarks have a result for both. Coding is ranked on the Vibe Coding Index; every other board is shown as published.

Replace Gemini 3.1 Flash Lite Preview Replace GPT-5.6 Luna
Gemini 3.1 Flash Lite PreviewGoogle
Coding
8.1
Overall
15.6
Output $/M
$1.50
9
GPT-5.6 LunaOpenAI
Coding
61.5
Overall
37.3
Output $/M
$1.20
62
vs boards won of 72 shared, 1 tied

Decision reading

Pick GPT-5.6 Luna for coding: it scores 61.5 on the Vibe Coding Index against 8.1 for Gemini 3.1 Flash Lite Preview.

Pick Gemini 3.1 Flash Lite Preview when what matters is MMLU Pro or MortgageTax (Vals AI), where it leads.

Model AGemini 3.1 Flash Lite PreviewGoogle8.1/1001 independent benchmark$0.18 per solved taskModel BGPT-5.6 LunaOpenAI61.5/1002 independent benchmarks$0.04 per solved task
Shared results
72
Gemini 3.1 Flash Lite Preview only
5
GPT-5.6 Luna only
44
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
Gemini 3.1 Flash Lite Preview 8.1 from 1 benchmark, GPT-5.6 Luna 61.5 from 2 benchmarks.
Widest category
Agentic work, 35.8 points apart on average over 5 shared benchmarks.
Widest single gap
Vibe Code Bench (Vals AI): Gemini 3.1 Flash Lite Preview 0.0% against GPT-5.6 Luna 77.1%, 77.1 points apart on a 0 to 100 scale.
Output price
Gemini 3.1 Flash Lite Preview $1.50 against GPT-5.6 Luna $1.20 per million output tokens, 1.3x apart.
Context window
Gemini 3.1 Flash Lite Preview 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 3.1 Flash Lite PreviewBarsGPT-5.6 LunaTies
Coding0121 tie
Intelligence01
Agentic work05
Reasoning07
Math02
Knowledge46
Web design17
General422
All shared boards9621 tie
CodingLike-for-likeFour of these boards feed the Vibe Coding Index012
Coding benchmarks for Gemini 3.1 Flash Lite Preview and GPT-5.6 Luna
BenchmarkGemini 3.1 Flash Lite PreviewGPT-5.6 LunaLeader
LiveBench codingNot measured73.6%Only GPT-5.6 Luna measured
LMArena WebDev12571518GPT-5.6 Luna
AA Coding Index34.771.4GPT-5.6 Luna
LiveCodeBench (Vals AI)80.1%Not measuredOnly Gemini 3.1 Flash Lite Preview measured
SWE-bench Verified (Vals AI)62.8%93.0%GPT-5.6 Luna
Terminal-Bench 4 (Vals AI)Not measured11.6%Only GPT-5.6 Luna measured
Vibe Code Bench (Vals AI)0.0%77.1%GPT-5.6 Luna
Code migration (Vals AI)4.6%44.5%GPT-5.6 Luna
ProgramBench (Vals AI)0.0%0.0%Tie
IOI (Vals AI)Not measured61.8%Only GPT-5.6 Luna measured
Terminal-Bench 2.1 (Vals AI)34.1%79.0%GPT-5.6 Luna
Vibe Code Bench 1-100 (Vals AI)Not measured22.6%Only GPT-5.6 Luna measured
SkillsBench (Vals AI)Not measured60.5%Only GPT-5.6 Luna measured
CyberBench (Vals AI)Not measured73.6%Only GPT-5.6 Luna measured
SciCodeNot measured53.6%Only GPT-5.6 Luna measured
FrontierCodeNot measured39.8%Only GPT-5.6 Luna measured
WeirdMLNot measured60.9%Only GPT-5.6 Luna measured
ALE-Bench797.71667.4GPT-5.6 Luna
LMArena Text: coding14001466GPT-5.6 Luna
LMArena Text: software and IT14131463GPT-5.6 Luna
LMArena WebDev: React12451508GPT-5.6 Luna
LMArena WebDev: HTML12761520GPT-5.6 Luna
LMArena WebDev: from an image13361517GPT-5.6 Luna
Neither model has a result on the other 15 boards here
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index01
Intelligence benchmarks for Gemini 3.1 Flash Lite Preview and GPT-5.6 Luna
BenchmarkGemini 3.1 Flash Lite PreviewGPT-5.6 LunaLeader
AA Intelligence Index15.637.3GPT-5.6 Luna
Epoch Capabilities IndexNot measured156.5Only GPT-5.6 Luna measured
Agentic workLike-for-likePublic boards, shown as published, kept out of the index05
Agentic work benchmarks for Gemini 3.1 Flash Lite Preview and GPT-5.6 Luna
BenchmarkGemini 3.1 Flash Lite PreviewGPT-5.6 LunaLeader
AA Agentic Index1.642.1GPT-5.6 Luna
LiveBench researchNot measured51.0%Only GPT-5.6 Luna measured
LiveBench browserNot measured68.0%Only GPT-5.6 Luna measured
LiveBench long agenticNot measured30.4%Only GPT-5.6 Luna measured
SREBench (Vals AI)Not measured1.5%Only GPT-5.6 Luna measured
Finance Agent (Vals AI)30.0%55.0%GPT-5.6 Luna
Tax Agent Bench (Vals AI)3.1%24.8%GPT-5.6 Luna
Legal Research Bench (Vals AI)3.4%36.5%GPT-5.6 Luna
Excel Modeling Benchmark (Vals AI)8.6%67.1%GPT-5.6 Luna
BioMysteryBench (Vals AI)Not measured61.5%Only GPT-5.6 Luna measured
Terminal-Bench-Science (Vals AI)Not measured0.0%Only GPT-5.6 Luna measured
Vals Science IndexNot measured25.3%Only GPT-5.6 Luna measured
APEX-AgentsNot measured43.0%Only GPT-5.6 Luna measured
BALROGNot measured45.6%Only GPT-5.6 Luna measured
Vending-Bench 2Not measured$4,095Only GPT-5.6 Luna measured
Neither model has a result on the other 24 boards here
ReasoningLike-for-likePublic boards, shown as published, kept out of the index07
Reasoning benchmarks for Gemini 3.1 Flash Lite Preview and GPT-5.6 Luna
BenchmarkGemini 3.1 Flash Lite PreviewGPT-5.6 LunaLeader
GPQA Diamond81.1%91.7%GPT-5.6 Luna
LiveBench reasoningNot measured85.6%Only GPT-5.6 Luna measured
MysteryMechanism (Vals AI)Not measured14.4%Only GPT-5.6 Luna measured
MMMU Pro (Vals AI)82.5%85.0%GPT-5.6 Luna
GPQA Diamond (Artificial Analysis run)Not measured91.1%Only GPT-5.6 Luna measured
Humanity's Last Exam (Artificial Analysis run)Not measured39.5%Only GPT-5.6 Luna measured
GPQA Diamond (Epoch AI run)Not measured91.6%Only GPT-5.6 Luna measured
ARC-AGINot measured88.0%Only GPT-5.6 Luna measured
ARC-AGI-2Not measured59.5%Only GPT-5.6 Luna measured
SimpleBenchNot measured46.8%Only GPT-5.6 Luna measured
Chess puzzlesNot measured43.0%Only GPT-5.6 Luna measured
Mystery game puzzlesNot measured21.0%Only GPT-5.6 Luna measured
LMArena Text: hard prompts14071451GPT-5.6 Luna
LMArena Text: expert13981478GPT-5.6 Luna
LMArena Text: hard prompts in English14031460GPT-5.6 Luna
LMArena Vision: diagrams12421273GPT-5.6 Luna
LMArena Vision: homework12711282GPT-5.6 Luna
Neither model has a result on the other 4 boards here
MathLike-for-likePublic boards, shown as published, kept out of the index02
Math benchmarks for Gemini 3.1 Flash Lite Preview and GPT-5.6 Luna
BenchmarkGemini 3.1 Flash Lite PreviewGPT-5.6 LunaLeader
AIME83.3%Not measuredOnly Gemini 3.1 Flash Lite Preview measured
OTIS Mock AIMENot measured98.3%Only GPT-5.6 Luna measured
FrontierMath, tiers 1 to 3Not measured82.1%Only GPT-5.6 Luna measured
FrontierMath, tier 4Not measured61.0%Only GPT-5.6 Luna measured
ProofBenchNot measured60.0%Only GPT-5.6 Luna measured
LMArena Text: math14281459GPT-5.6 Luna
LMArena Text: mathematical work14171470GPT-5.6 Luna
Neither model has a result on the other 6 boards here
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index46
Knowledge benchmarks for Gemini 3.1 Flash Lite Preview and GPT-5.6 Luna
BenchmarkGemini 3.1 Flash Lite PreviewGPT-5.6 LunaLeader
MMLU Pro86.2%86.0%Gemini 3.1 Flash Lite Preview
LegalBench (Vals AI)83.8%84.0%GPT-5.6 Luna
CaseLaw (Vals AI)55.0%Not measuredOnly Gemini 3.1 Flash Lite Preview measured
CorpFin (Vals AI)59.4%64.2%GPT-5.6 Luna
TaxEval (Vals AI)71.8%76.2%GPT-5.6 Luna
MortgageTax (Vals AI)68.0%67.3%Gemini 3.1 Flash Lite Preview
MedCode (Vals AI)47.6%42.4%Gemini 3.1 Flash Lite Preview
SimpleQA VerifiedNot measured41.0%Only GPT-5.6 Luna measured
LMArena Text: science14251433GPT-5.6 Luna
LMArena Text: medicine and healthcare14281399Gemini 3.1 Flash Lite Preview
LMArena Text: legal and government14181446GPT-5.6 Luna
LMArena Text: business and finance13891439GPT-5.6 Luna
Neither model has a result on the other 5 boards here
Web designLike-for-likePublic boards, shown as published, kept out of the index17
Web design benchmarks for Gemini 3.1 Flash Lite Preview and GPT-5.6 Luna
BenchmarkGemini 3.1 Flash Lite PreviewGPT-5.6 LunaLeader
Design Arena: websites10831256GPT-5.6 Luna
Design Arena: UI components10711250GPT-5.6 Luna
Design Arena: game dev10291196GPT-5.6 Luna
Design Arena: data viz10451212GPT-5.6 Luna
Design Arena: 3D10481121GPT-5.6 Luna
Design Arena: all code categories10721231GPT-5.6 Luna
Design Arena: SVG10521193GPT-5.6 Luna
Design Arena: ASCII art11661144Gemini 3.1 Flash Lite Preview
LiveBench designNot measured76.0%Only GPT-5.6 Luna measured
GeneralLike-for-likePublic boards, shown as published, kept out of the index422
General benchmarks for Gemini 3.1 Flash Lite Preview and GPT-5.6 Luna
BenchmarkGemini 3.1 Flash Lite PreviewGPT-5.6 LunaLeader
LiveBench data analysisNot measured78.0%Only GPT-5.6 Luna measured
Public Benefits Bench (Vals AI)Not measured61.2%Only GPT-5.6 Luna measured
SAGE (Vals AI)49.5%44.2%Gemini 3.1 Flash Lite Preview
MedScribe (Vals AI)63.9%84.4%GPT-5.6 Luna
Vals Multimodal Index41.4%69.1%GPT-5.6 Luna
Long context reasoning (AA-LCR)Not measured83.7%Only GPT-5.6 Luna measured
DTBenchNot measured89.1%Only GPT-5.6 Luna measured
LMCANot measured48.5%Only GPT-5.6 Luna measured
Surface Evolver BenchNot measured61.9%Only GPT-5.6 Luna measured
Furniture assemblyNot measured42.5%Only GPT-5.6 Luna measured
LMArena Text14161431GPT-5.6 Luna
LMArena Text: instruction following13771437GPT-5.6 Luna
LMArena Text: creative writing14011396Gemini 3.1 Flash Lite Preview
LMArena Vision12401257GPT-5.6 Luna
LMArena Text: English14141441GPT-5.6 Luna
LMArena Text: non-English14101417GPT-5.6 Luna
LMArena Text: Chinese14601470GPT-5.6 Luna
LMArena Text: German14301455GPT-5.6 Luna
LMArena Text: Japanese14131415GPT-5.6 Luna
LMArena Text: Korean13921415GPT-5.6 Luna
LMArena Text: French14241458GPT-5.6 Luna
LMArena Text: Spanish14211446GPT-5.6 Luna
LMArena Text: Russian14201427GPT-5.6 Luna
LMArena Text: Polish14431405Gemini 3.1 Flash Lite Preview
LMArena Text: multi-turn14171434GPT-5.6 Luna
LMArena Text: longer queries13941436GPT-5.6 Luna
LMArena Text: writing and language14081419GPT-5.6 Luna
LMArena Text: entertainment and media13861402GPT-5.6 Luna
LMArena Vision: English12321263GPT-5.6 Luna
LMArena Vision: Chinese12781294GPT-5.6 Luna
LMArena Vision: reading text12461264GPT-5.6 Luna
LMArena Vision: humor12661190Gemini 3.1 Flash Lite Preview
LMArena Vision: captioning1259Not measuredOnly Gemini 3.1 Flash Lite Preview measured
LMArena Vision: recognizing things1308Not measuredOnly Gemini 3.1 Flash Lite Preview measured
LMArena Vision: creative writing12481257GPT-5.6 Luna
LMArena DocumentNot measured1457Only GPT-5.6 Luna 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 Gemini 3.1 Flash Lite Preview and GPT-5.6 Luna
BenchmarkGemini 3.1 Flash Lite PreviewGPT-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 3.1 Flash Lite Preview$0.0010Fits 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 3.1 Flash Lite Preview$0.017Fits 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 3.1 Flash Lite Preview$0.065Fits 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 3.1 Flash Lite Preview and GPT-5.6 Luna
SpecificationGoogle Gemini 3.1 Flash Lite PreviewOpenAI GPT-5.6 Luna
MakerGoogleOpenAI
WeightsNo public weights listedNo public weights listed
ReleasedMarch 3, 2026July 9, 2026
Context window1.05M1.05M
Input $/Mtok$0.25$0.20
Output $/Mtok$1.50$1.20
Coding index8.161.5
Independent measurements behind it12
Cost per solved task$0.18$0.04
SourceOpenRouter listingOpenRouter listing

Questions

Is Gemini 3.1 Flash Lite Preview better than GPT-5.6 Luna for coding?

Pick GPT-5.6 Luna for coding: it scores 61.5 on the Vibe Coding Index against 8.1 for Gemini 3.1 Flash Lite Preview. Pick Gemini 3.1 Flash Lite Preview when what matters is MMLU Pro or MortgageTax (Vals AI), where it leads.

Which is cheaper, Gemini 3.1 Flash Lite Preview or GPT-5.6 Luna?

Gemini 3.1 Flash Lite Preview costs $0.25 per million input tokens and $1.50 per million output tokens; GPT-5.6 Luna costs $0.20 and $1.20. Per solved SWE-bench Verified task, Gemini 3.1 Flash Lite Preview costs $0.18 and GPT-5.6 Luna $0.04.

Which has the bigger context window, Gemini 3.1 Flash Lite Preview or GPT-5.6 Luna?

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

How many benchmarks is the Gemini 3.1 Flash Lite Preview vs GPT-5.6 Luna comparison based on?

72 benchmarks have a result for both models as of October 21, 2026. Gemini 3.1 Flash Lite Preview's coding index rests on 1 independent benchmark and GPT-5.6 Luna's on 2. Where only one model has a result, the page says so instead of naming a winner.

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