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Gemini 3.5 Flash Lite vs GPT-5.6 Luna

GPT-5.6 Luna leads Gemini 3.5 Flash Lite on coding, 58.0 to 49.0 on the Vibe Coding Index, and GPT-5.6 Luna costs 2.1x less per output token ($1.20 vs $2.50 per million). Updated October 22, 2026; 84 benchmarks have a result for both.

Replace Gemini 3.5 Flash Lite Replace GPT-5.6 Luna
Gemini 3.5 Flash LiteGoogle
Coding
49.0
Overall
49.8
Output $/M
$2.50
24
GPT-5.6 LunaOpenAI
Coding
58.0
Overall
61.6
Output $/M
$1.20
58
vs boards won of 84 shared, 2 tied

Gemini 3.5 Flash Lite or GPT-5.6 Luna: which to pick

Pick GPT-5.6 Luna for coding: it scores 58.0 on the Vibe Coding Index against 49.0 for Gemini 3.5 Flash Lite.

Pick Gemini 3.5 Flash Lite for work measured by LMArena Vision: diagrams or LMArena Vision: homework, where it leads.

Model AGemini 3.5 Flash LiteGoogle49.0/1003 independent benchmarks$0.41 per solved taskModel BGPT-5.6 LunaOpenAI58.0/1006 independent benchmarks$0.04 per solved task
Shared results
84
Gemini 3.5 Flash Lite only
1
GPT-5.6 Luna only
35
Like-for-like categories
7 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 3.5 Flash Lite 49.0 from 3 benchmarks, GPT-5.6 Luna 58.0 from 6 benchmarks.
Widest category
Math, 33.6 points apart on average over 6 shared benchmarks.
Widest single gap
FrontierMath, tier 4: Gemini 3.5 Flash Lite 0.0% against GPT-5.6 Luna 61.0%, 61.0 points apart on a 0 to 100 scale.
Output price
Gemini 3.5 Flash Lite $2.50 against GPT-5.6 Luna $1.20 per million output tokens, 2.1x apart.
Context window
Gemini 3.5 Flash Lite 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 3.5 Flash LiteBarsGPT-5.6 LunaTies
Coding0142 ties
Intelligence02
Agentic work06
Reasoning212
Math06
Knowledge65
General1613
All shared boards24582 ties
CodingLike-for-likeSix of these boards feed the Vibe Coding Index014
Coding benchmarks for Gemini 3.5 Flash Lite and GPT-5.6 Luna
BenchmarkGemini 3.5 Flash LiteGPT-5.6 LunaLeader
LiveBench codingNot measured73.6%Only GPT-5.6 Luna measured
LMArena WebDev14351518GPT-5.6 Luna
AA Coding Index49.371.4GPT-5.6 Luna
LiveCodeBench (Vals AI)79.0%Not measuredOnly Gemini 3.5 Flash Lite measured
SWE-bench Verified (Vals AI)75.0%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)37.2%77.1%GPT-5.6 Luna
Code migration (Vals AI)6.2%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)50.2%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)59.1%73.6%GPT-5.6 Luna
SciCode41.3%53.6%GPT-5.6 Luna
FrontierCodeNot measured39.8%Only GPT-5.6 Luna measured
WeirdML39.0%60.9%GPT-5.6 Luna
ALE-Bench765.31667.4GPT-5.6 Luna
LMArena Text: coding14531466GPT-5.6 Luna
LMArena Text: software and IT14511463GPT-5.6 Luna
LMArena WebDev: React14081508GPT-5.6 Luna
LMArena WebDev: HTMLNot measured1520Only GPT-5.6 Luna measured
LMArena WebDev: from an image14481517GPT-5.6 Luna
SciCode6.2%6.2%Tie
Neither model has a result on the other 15 boards here
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index02
Intelligence benchmarks for Gemini 3.5 Flash Lite and GPT-5.6 Luna
BenchmarkGemini 3.5 Flash LiteGPT-5.6 LunaLeader
AA Intelligence Index22.237.3GPT-5.6 Luna
Epoch Capabilities Index144.9156.5GPT-5.6 Luna
Agentic workLike-for-likePublic boards, shown as published, kept out of the index06
Agentic work benchmarks for Gemini 3.5 Flash Lite and GPT-5.6 Luna
BenchmarkGemini 3.5 Flash LiteGPT-5.6 LunaLeader
AA Agentic Index14.342.1GPT-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)47.4%55.0%GPT-5.6 Luna
Tax Agent Bench (Vals AI)7.2%24.8%GPT-5.6 Luna
Legal Research Bench (Vals AI)13.9%36.5%GPT-5.6 Luna
Excel Modeling Benchmark (Vals AI)43.2%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-Agents29.3%43.0%GPT-5.6 Luna
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 26 boards here
ReasoningLike-for-likePublic boards, shown as published, kept out of the index212
Reasoning benchmarks for Gemini 3.5 Flash Lite and GPT-5.6 Luna
BenchmarkGemini 3.5 Flash LiteGPT-5.6 LunaLeader
GPQA Diamond83.8%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)83.6%85.0%GPT-5.6 Luna
GPQA Diamond (Artificial Analysis run)83.8%91.1%GPT-5.6 Luna
Humanity's Last Exam (Artificial Analysis run)18.8%39.5%GPT-5.6 Luna
GPQA Diamond (Epoch AI run)83.3%91.6%GPT-5.6 Luna
ARC-AGI53.5%88.0%GPT-5.6 Luna
ARC-AGI-210.3%59.5%GPT-5.6 Luna
SimpleBenchNot measured46.8%Only GPT-5.6 Luna measured
Chess puzzles21.0%43.0%GPT-5.6 Luna
Mystery game puzzles19.0%21.0%GPT-5.6 Luna
LMArena Text: hard prompts14411451GPT-5.6 Luna
LMArena Text: expert14341478GPT-5.6 Luna
LMArena Text: hard prompts in English14401460GPT-5.6 Luna
LMArena Vision: diagrams12841273Gemini 3.5 Flash Lite
LMArena Vision: homework12911282Gemini 3.5 Flash Lite
Kagi LLM BenchmarkNot measured49.1%Only GPT-5.6 Luna measured
Neither model has a result on the other 4 boards here
MathLike-for-likePublic boards, shown as published, kept out of the index06
Math benchmarks for Gemini 3.5 Flash Lite and GPT-5.6 Luna
BenchmarkGemini 3.5 Flash LiteGPT-5.6 LunaLeader
OTIS Mock AIME71.1%98.3%GPT-5.6 Luna
FrontierMath, tiers 1 to 326.0%82.1%GPT-5.6 Luna
FrontierMath, tier 40.0%61.0%GPT-5.6 Luna
ProofBench13.0%60.0%GPT-5.6 Luna
LMArena Text: math14341459GPT-5.6 Luna
LMArena Text: mathematical work14331470GPT-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 index65
Knowledge benchmarks for Gemini 3.5 Flash Lite and GPT-5.6 Luna
BenchmarkGemini 3.5 Flash LiteGPT-5.6 LunaLeader
MMLU Pro85.8%86.0%GPT-5.6 Luna
LegalBench (Vals AI)84.1%84.0%Gemini 3.5 Flash Lite
CorpFin (Vals AI)60.7%64.2%GPT-5.6 Luna
TaxEval (Vals AI)72.6%76.2%GPT-5.6 Luna
MortgageTax (Vals AI)68.7%67.3%Gemini 3.5 Flash Lite
MedCode (Vals AI)43.5%42.4%Gemini 3.5 Flash Lite
SimpleQA VerifiedNot measured41.0%Only GPT-5.6 Luna measured
LMArena Text: science14511433Gemini 3.5 Flash Lite
LMArena Text: medicine and healthcare14381399Gemini 3.5 Flash Lite
LMArena Text: legal and government14311446GPT-5.6 Luna
LMArena Text: business and finance14231439GPT-5.6 Luna
FACTS Benchmark Suite53.5%35.0%Gemini 3.5 Flash Lite
Neither model has a result on the other 6 boards here
Web designDirectional onlyPublic boards, shown as published, kept out of the index9 boards, none shared
Web design benchmarks for Gemini 3.5 Flash Lite and GPT-5.6 Luna
BenchmarkGemini 3.5 Flash LiteGPT-5.6 LunaLeader
Design Arena: websitesNot measured1255Only GPT-5.6 Luna measured
Design Arena: UI componentsNot measured1248Only GPT-5.6 Luna measured
Design Arena: game devNot measured1194Only GPT-5.6 Luna measured
Design Arena: data vizNot measured1211Only GPT-5.6 Luna measured
Design Arena: 3DNot measured1121Only GPT-5.6 Luna measured
Design Arena: all code categoriesNot measured1231Only GPT-5.6 Luna measured
Design Arena: SVGNot measured1194Only GPT-5.6 Luna measured
Design Arena: ASCII artNot measured1142Only GPT-5.6 Luna measured
LiveBench designNot measured76.0%Only GPT-5.6 Luna measured
GeneralLike-for-likePublic boards, shown as published, kept out of the index1613
General benchmarks for Gemini 3.5 Flash Lite and GPT-5.6 Luna
BenchmarkGemini 3.5 Flash LiteGPT-5.6 LunaLeader
LiveBench data analysisNot measured78.0%Only GPT-5.6 Luna measured
Public Benefits Bench (Vals AI)51.8%61.2%GPT-5.6 Luna
SAGE (Vals AI)47.3%44.2%Gemini 3.5 Flash Lite
MedScribe (Vals AI)70.9%84.4%GPT-5.6 Luna
Vals Multimodal IndexNot measured69.1%Only GPT-5.6 Luna measured
Long context reasoning (AA-LCR)76.0%83.7%GPT-5.6 Luna
DTBench83.5%89.1%GPT-5.6 Luna
LMCA37.6%48.5%GPT-5.6 Luna
Surface Evolver BenchNot measured61.9%Only GPT-5.6 Luna measured
Furniture assemblyNot measured42.5%Only GPT-5.6 Luna measured
LMArena Text14351431Gemini 3.5 Flash Lite
LMArena Text: instruction following14191437GPT-5.6 Luna
LMArena Text: creative writing14211396Gemini 3.5 Flash Lite
LMArena Vision12691257Gemini 3.5 Flash Lite
LMArena Text: English14381441GPT-5.6 Luna
LMArena Text: non-English14271417Gemini 3.5 Flash Lite
LMArena Text: Chinese14681470GPT-5.6 Luna
LMArena Text: German14541455GPT-5.6 Luna
LMArena Text: Japanese14261415Gemini 3.5 Flash Lite
LMArena Text: Korean14071415GPT-5.6 Luna
LMArena Text: French14511458GPT-5.6 Luna
LMArena Text: Spanish14411446GPT-5.6 Luna
LMArena Text: Russian14431427Gemini 3.5 Flash Lite
LMArena Text: Polish14371405Gemini 3.5 Flash Lite
LMArena Text: multi-turn14451434Gemini 3.5 Flash Lite
LMArena Text: longer queries14351436GPT-5.6 Luna
LMArena Text: writing and language14281419Gemini 3.5 Flash Lite
LMArena Text: entertainment and media14141402Gemini 3.5 Flash Lite
LMArena Vision: English12691263Gemini 3.5 Flash Lite
LMArena Vision: Chinese13111294Gemini 3.5 Flash Lite
LMArena Vision: reading text12801264Gemini 3.5 Flash Lite
LMArena Vision: humor12871190Gemini 3.5 Flash Lite
LMArena Vision: creative writing12601257Gemini 3.5 Flash Lite
LMArena DocumentNot measured1457Only GPT-5.6 Luna measured
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 Gemini 3.5 Flash Lite and GPT-5.6 Luna
BenchmarkGemini 3.5 Flash LiteGPT-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 3.5 Flash Lite$0.0015Fits 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 3.5 Flash Lite$0.022Fits 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 3.5 Flash Lite$0.085Fits 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 3.5 Flash Lite and GPT-5.6 Luna
SpecificationGoogle Gemini 3.5 Flash LiteOpenAI GPT-5.6 Luna
MakerGoogleOpenAI
WeightsNo public weights listedNo public weights listed
ReleasedJuly 21, 2026July 9, 2026
Context window1.05M1.05M
Input $/Mtok$0.30$0.20
Output $/Mtok$2.50$1.20
Coding index49.058.0
Independent measurements behind it36
Cost per solved task$0.41$0.04
SourceOpenRouter listingOpenRouter listing

Questions

Is Gemini 3.5 Flash Lite better than GPT-5.6 Luna for coding?

Pick GPT-5.6 Luna for coding: it scores 58.0 on the Vibe Coding Index against 49.0 for Gemini 3.5 Flash Lite. Pick Gemini 3.5 Flash Lite for work measured by LMArena Vision: diagrams or LMArena Vision: homework, where it leads.

Which is cheaper, Gemini 3.5 Flash Lite or GPT-5.6 Luna?

Gemini 3.5 Flash Lite costs $0.30 per million input tokens and $2.50 per million output tokens; GPT-5.6 Luna costs $0.20 and $1.20. Per solved SWE-bench Verified task, Gemini 3.5 Flash Lite costs $0.41 and GPT-5.6 Luna $0.04.

Which has the bigger context window, Gemini 3.5 Flash Lite or GPT-5.6 Luna?

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

How many benchmarks is the Gemini 3.5 Flash Lite vs GPT-5.6 Luna comparison based on?

84 benchmarks have a result for both models as of October 22, 2026. Gemini 3.5 Flash Lite's coding index rests on 3 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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