BenchLeader

GPT-5.5 vs GPT-6 Luna

Full profiles: GPT-5.5 (OpenAI) and GPT-6 Luna (OpenAI): every benchmark, price and rank.

Updated · Data from 15 sources

As of 9 Nov 2026, GPT-5.5 is ahead of GPT-6 Luna on quality (64.3 vs 56.5 on the BenchLeader Index), but GPT-6 Luna is 56× cheaper at $0.200 vs $11.25 per 1M tokens blended. GPT-5.5 leads in every category we measure both in.

Key facts (as of 9 Nov 2026)

  • GPT-5.5 scores 64.3 on the BenchLeader Index and GPT-6 Luna scores 56.5 (BenchLeader, 9 Nov 2026).
  • GPT-5.5 costs $11.25 per 1M tokens blended (list price, 9 Nov 2026).
  • GPT-6 Luna costs $0.200 per 1M tokens blended (list price, 9 Nov 2026).
  • Of the 44 benchmarks both models have, GPT-5.5 leads 36 (BenchLeader, 9 Nov 2026).
  • On Arena WebDev, GPT-5.5 is rated 1512 and GPT-6 Luna 1577 (LMArena, as published by 9 Nov 2026).

Which to pick for…

The pick's numbers come first. Category scores on the BenchLeader scale (50 is the average model, 15 points one standard deviation). High confidence means a lead of half a standard deviation or more; under one point is called either.

Use casePickWhyConfidence
CodingGPT-5.561 vs 58 category score; SciCode 55.8% vs 54.6%Medium
Agents & tool useGPT-5.562 vs 49 category score; LiveBench Agentic Coding 54.0% vs 51.2%High
MathsGPT-5.570 vs 64 category score; FrontierMath Tiers 1–3 85.3% vs 79.0%Medium
ReasoningGPT-5.568 vs 56 category score; ARC-AGI-2 85.0% vs 59.3%High
KnowledgeGPT-5.564 vs 45 category score; SimpleQA Verified 63.0% vs 41.4%High
Long documentsEither67 vs 66 category score; AA-LCR v1.1 84.3% vs 83.3%Either
Images and other mediaGPT-5.562 vs 58 category score; MMMU-Pro 79.9% vs 79.7%Medium
Chat quality (human preference)–Only GPT-6 Luna has an Arena rating (62 category score)Not comparable
Lowest costGPT-6 Luna$0.200 vs $11.25 per 1M blended; agentic coding session $0.008 vs $0.420–
Fastest first answerGPT-5.544.1 s (GPT-5.5 (xhigh)) vs 85.0 s (GPT-6 Luna (max)) to the first answer token–
High volume on a budgetNeither flagshipA smaller model is usually the better fit: Cheapest good LLMs, Fastest LLMs–

Key differences

  • GPT-5.5 (xhigh) leads on quality: 64.3 vs 56.5.
  • GPT-5.5 (xhigh) is stronger in agents & tools, coding, instruction following, knowledge, long context, maths, multimodal, reasoning.
  • GPT-6 Luna (max) is stronger in human preference.
  • GPT-6 Luna (max) is 56× cheaper ($0.200 vs $11.25 per 1M blended).

At a glance

SpecGPT-5.5GPT-6 Luna
DeveloperOpenAIOpenAI
Released23 Apr 202622 Sep 2026
Context window (tokens)1,050,0001,050,000
Compared atGPT-5.5 (xhigh)GPT-6 Luna (max)
Open weightsNoNo
Price in / out / cached input per 1M$5.00 / $30.00 / $0.500$0.100 / $0.500 / $0.010

Category by category

Category scores on the BenchLeader scale: 50 is the average evaluated model, 15 points is one standard deviation. A gap under one point is called level.

CategoryGPT-5.5 (xhigh)GPT-6 Luna (max)Leader
Reasoning68.355.9GPT-5.5
Coding61.057.5GPT-5.5
Agents & tools61.848.5GPT-5.5
Maths69.864.1GPT-5.5
Knowledge64.045.1GPT-5.5
Instruction following74.0–not comparable
Human preference–62.2not comparable
Multimodal62.357.6GPT-5.5
Long context67.066.4level

On one chart

Each domain on the index's own scale, where 50 is an average model. Click a domain to see the benchmarks behind it. Pick up to 5 models from the list.

2550 avg75ReasoningCodingAgents & toolsMathsKnowledgeLong contextMultimodalGPT-5.5, Reasoning: 68.3GPT-5.5, Coding: 61.0GPT-5.5, Agents & tools: 61.8GPT-5.5, Maths: 69.8GPT-5.5, Knowledge: 64.0GPT-5.5, Long context: 67.0GPT-5.5, Multimodal: 62.3GPT-6 Luna, Reasoning: 55.9GPT-6 Luna, Coding: 57.5GPT-6 Luna, Agents & tools: 48.5GPT-6 Luna, Maths: 64.1GPT-6 Luna, Knowledge: 45.1GPT-6 Luna, Long context: 66.4GPT-6 Luna, Multimodal: 57.6

Not drawn, measured for fewer than two of these models: Instruction following, Human preference.

ModelIndex

Where sources disagree

Across the 44 benchmarks both have, GPT-5.5 leads 36, GPT-6 Luna leads 7 and 1 is a tie. Every overall index that rates both puts GPT-5.5 ahead.

Overall indexGPT-5.5 (xhigh)GPT-6 Luna (max)Leader
BenchLeader Index64.356.5GPT-5.5
Arena Text1481†1441GPT-5.5

Each publisher runs its own tasks, harnesses and effort settings, so their overall verdicts can differ; BenchLeader reconciles them on one scale. † measured at another effort setting of the same model (the publisher did not test the one compared here).

Price, speed and latency

List prices blended at three input tokens per output token. Per-task prices use the token counts on the methodology page. Cost, tokens and time per benchmark task are measured: Artificial Analysis’ averages over its whole Intelligence Index run.

MeasureGPT-5.5 (xhigh)GPT-6 Luna (max)
Blended price per 1M tokens$11.25$0.200
Input / output per 1M$5.00 / $30.00$0.100 / $0.500
Cached input per 1M$0.500$0.010
Price per task: chat reply$0.011$0.0002
Price per task: summarize a 30-page report$0.078$0.0015
Price per task: code edit$0.075$0.0014
Price per task: agentic coding session$0.420$0.0080
Price per task: structured extraction$0.016$0.0003
Agentic coding session, input mostly cached$0.217$0.0040
Cost per benchmark task (AA Index)–$0.152
Output tokens per task (AA Index)–75k
Of which reasoning–58k
Time per task (AA Index)–12 min
Output speed80 tok/s104 tok/s
Time to first answer44.1 s85.0 s
Time to a complete answer98.5 s177.1 s

Each model is compared at its best-ranked reasoning-effort setting. GPT-5.5 (xhigh) scores 64.3 and takes 44 s to its first answer token; GPT-5.5 (high) scores 63.7 in 23 s, GPT-5.5 scores 61.7 in 2 s. GPT-6 Luna (max) scores 56.5 and takes 85 s to its first answer token; GPT-6 Luna (xhigh) scores 52.1 in 22 s, GPT-6 Luna (high) scores 51.2 in 11 s. Higher effort means more thinking before the answer: better scores, longer waits and more tokens billed. How reasoning effort changes scores and cost.

Every benchmark

174 benchmarks, grouped by category; each name links to the board and its leaders. † measured at another effort setting of the same model, shown for reference and not counted as a win.

MetricPublisherGPT-5.5 (xhigh)GPT-6 Luna (max)
BenchLeader IndexBenchLeader64.356.5
Agents & tools scoreBenchLeader61.848.5
Coding scoreBenchLeader61.057.5
Instruction following scoreBenchLeader74.0–
Knowledge scoreBenchLeader64.045.1
Long context scoreBenchLeader67.066.4
Maths scoreBenchLeader69.864.1
Multimodal scoreBenchLeader62.357.6
Reasoning scoreBenchLeader68.355.9
Human preference scoreBenchLeader–62.2
Blended price $/MBenchLeader$11.25$0.200
Output speedBenchLeader80 tok/s104 tok/s
Time to first answerBenchLeader44.1 s85.0 s
Context windowBenchLeader1,050,000 tokens1,050,000 tokens
Reasoning
GPQA DiamondEpoch AI Benchmarking Hub90.7%†90.5%
SimpleBenchSimpleBench69.0%†–
Arena Hard PromptsArena (LMArena)1499†1463
LiveBench 2.0 ReasoningLiveBench–81.8%†
LiveBench 1.0 ReasoningLiveBench89.7%81.8%
GPQA Diamond (AA)Artificial Analysis93.5%–
Humanity's Last Exam (AA)Artificial Analysis45.8%38.5%
HLE-Diamond (AA)Artificial Analysis–22.2%
GPQA Diamond (Vals)Vals AI93.2%–
Kagi LLM BenchmarkKagi LLM Benchmark88.8%†–
ARC-AGI-1ARC Prize95.0%86.7%
ARC-AGI-2ARC Prize85.0%59.3%
ARC-AGI-3ARC Prize0.4%†0.6%
CritPtArtificial Analysis27.1%19.4%
CritPt v2 hard subset (AA)Artificial Analysis–42.5%
MysteryMechanismVals AI–19.4%
Chess PuzzlesEpoch AI Benchmarking Hub63.0%36.0%
Mystery Game PuzzlesEpoch AI Benchmarking Hub56.0%7.0%
CL-bench LifeEpoch AI Benchmarking Hub22.2%†–
LMCAEpoch AI Benchmarking Hub54.3%44.5%
DTBenchEpoch AI Benchmarking Hub96.0%90.1%
ForecastBenchForecastBench64.5%†–
BTF-3Epoch AI Benchmarking Hub14.3%†–
Coding
SciCodeSciCode55.8%54.6%
WeirdMLWeirdML84.9%–
Show all 174 benchmarks
MetricPublisherGPT-5.5 (xhigh)GPT-6 Luna (max)
Coding
FrontierCodeCognition43.0%†42.4%
GSO-BenchGSO-Bench40.2%–
Arena CodingArena (LMArena)1510†1502
Arena WebDevArena (LMArena)15121577
LiveBench 2.0 CodingLiveBench–70.8%†
LiveBench 1.0 CodingLiveBench82.2%79.0%
LiveCodeBenchVals AI85.3%–
IOIVals AI–55.6%
SWE-bench (Vals)Vals AI82.6%–
Code MigrationVals AI45.2%42.5%
Code Migration v1.1Vals AI–46.7%
ProgramBenchVals AI0.5%0.5%
SWE-bench MultimodalVals AI–37.5%
Vibe Code Bench v1.1Vals AI69.8%81.7%
SWE Atlas: Codebase QnAScale AI SEAL45.4%–
SWE Atlas: RefactoringScale AI SEAL44.8%–
SWE Atlas: Test WritingScale AI SEAL42.6%–
MirrorCodeEpoch AI Benchmarking Hub10.0%†26.7%
Surface Evolver BenchEpoch AI Benchmarking Hub88.1%†–
DeepSWE v1.1Epoch AI Benchmarking Hub67.0%–
ALE-BenchEpoch AI Benchmarking Hub1943.01576.9†
Terminal-Bench 4.0 (AA)Artificial Analysis14.7%12.6%
Terminal-Bench 2.1 (AA)Artificial Analysis84.3%–
Startrise FrontendStartrise–69.3%†
GameBench 2 OverallDuelLab GameBench 249.0†47.1†
GameBench 2 by reasoning settingDuelLab GameBench 259.755.8†
Design Arena WebsiteDesign Arena1253†1265†
FrontierCode 1.1 (AA)Artificial Analysis–41.9%
FrontierCode 2.0 (AA)Artificial Analysis–25.2%
Agents & tools
Terminal-BenchTerminal-Bench84.7%†15.2%
OSWorld-Verified 2.0OSWorld13.0%–
Remote Labor IndexScale AI / CAIS6.3%†–
APEX-AgentsMercor55.1%†44.3%
Arena AgentArena (LMArena)–1.5
LiveBench Long AgenticLiveBench–24.7%†
LiveBench BrowserLiveBench–70.3%†
LiveBench Agentic CodingLiveBench54.0%51.2%
Terminal-Bench HardArtificial Analysis60.6%–
τ²-Bench Telecom (AA)Artificial Analysis93.9%–
Terminal-Bench 2.1 (Vals)Vals AI76.4%†73.0%
MCP AtlasScale AI SEAL75.3%–
HiL-BenchScale AI SEAL39.7%†–
τ³-bench Bankingτ²-bench44.6%–
GDPval-AA v2.1, normalised scoreArtificial Analysis–46.6%
GDPval-AA v2.1Artificial Analysis–1444
τ³-Banking (AA)Artificial Analysis39.0%–
ITBench SRE (AA)Artificial Analysis45.8%–
Analyst Agent (AA)Artificial Analysis50.0%43.8%
APEX-Agents (AA)Artificial Analysis37.7%–
CyberBenchVals AI–76.3%
Finance Agent v2Vals AI51.8%49.9%
Finance Agent v2.1Vals AI–56.8%
Harvey's Legal Agent Benchmark v1.1Vals AI–4.2%
Harvey's Legal Agent Benchmark v1Vals AI3.8%2.9%
Legal Research BenchVals AI40.4%30.3%
SkillsBenchVals AI62.2%–
SREBenchVals AI3.8%2.7%
Tax Agent BenchVals AI21.8%19.9%
Terminal-Bench 2.0 (Vals)Vals AI73.2%†–
Terminal-Bench 4.0 (Vals)Vals AI–13.6%
Terminal-Bench ScienceVals AI–4.3%
Time Horizon Index: KSPVals AI8.3%–
Arena SearchArena (LMArena)1226†1211
DeepResearch BenchDeepResearch Bench54.0%†–
PostTrainBenchEpoch AI Benchmarking Hub27.2%–
ExploitBenchEpoch AI Benchmarking Hub47.4%†–
GBAEvalEpoch AI Benchmarking Hub53.2%†–
Vending-Bench 2Andon Labs7523.8†–
AutomationBenchArtificial Analysis47.3%53.2%
GDP.pdf (AA)Artificial Analysis21.2%22.8%
Harvey LAB-AA v1.1Harvey–3.3%
EnterpriseOps-GymArtificial Analysis46.6%–
AA-Briefcase v1.1Artificial Analysis11351337
GDPxGDPx by SemiAnalysis–5.1%
Design Arena AgenticDesign Arena1108†1149†
Terminal-Bench-Science 0.1 (AA)Artificial Analysis–8.6%
CWE-Bench (AA)Artificial Analysis–56.7%
DeepSec-Bench (AA)Artificial Analysis–23.5%
CyberGym end-to-end (AA)Artificial Analysis–77.9%
FACTS SearchGoogle–86.8%†
Maths
FrontierMath Tiers 1–3Epoch AI Benchmarking Hub85.3%79.0%
FrontierMath Tier 4Epoch AI Benchmarking Hub72.5%56.1%
OTIS Mock AIMEEpoch AI Benchmarking Hub84.4%†98.9%
ProofBenchVals AI50.0%64.0%†
LiveBench MathematicsLiveBench95.9%89.1%
AIME 2026MathArena100.0%–
HMMT February 2026MathArena98.5%–
USAMO 2026MathArena98.2%–
MathArena ApexMathArena80.2%–
Arena MathsArena (LMArena)1500†1450
Knowledge
SimpleQA VerifiedEpoch AI Benchmarking Hub63.0%41.4%
LiveBench 2.0 Data AnalysisLiveBench–73.4%†
LiveBench ResearchLiveBench–48.5%†
LiveBench 1.0 Data AnalysisLiveBench81.6%73.4%
AA-Omniscience v1.1Artificial Analysis–-8.3
MMLU-ProVals AI88.1%–
LegalBenchVals AI86.5%–
CorpFinVals AI68.4%–
TaxEvalVals AI75.0%–
PRBench LegalScale AI SEAL–42.9%†
BioMysteryBenchVals AI–61.5%
CaseLaw v2Vals AI66.2%–
ClaimBenchVals AI–99.2%
Excel Modeling BenchmarkVals AI64.5%68.5%
Excel Modeling Benchmark v1.1Vals AI–70.0%
MedCodeVals AI49.1%44.7%
MedScribeVals AI86.9%83.7%
Public Benefits Bench v1.1Vals AI60.9%57.6%
DrugDiscoveryBenchScale AI SEAL51.6%–
EBR-benchEpoch AI Benchmarking Hub34.3%–
GDP.pdfEpoch AI Benchmarking Hub26.0%23.0%
AA-Omniscience v1.1: accuracyArtificial Analysis–39.6%
AA-Omniscience v1.1: non-hallucinationArtificial Analysis–20.6%
HealthBench Professional (AA)OpenAI–61.9%
Instruction following
LiveBench LanguageLiveBench87.4%73.8%
LiveBench Instruction FollowingLiveBench70.7%55.9%
IFBenchArtificial Analysis75.8%–
Arena Instruction FollowingArena (LMArena)1475†1436
Human preference
Arena TextArena (LMArena)1476†1441
EQ-Bench 4EQ-Bench1295†–
Arena Creative WritingArena (LMArena)1448†1407
Arena Multi-turnArena (LMArena)1484†1442
Arena Longer QueriesArena (LMArena)1487†1448
Multimodal
Arena VisionArena (LMArena)1296†1211
LiveBench DesignLiveBench–76.1%†
MMMU-ProArtificial Analysis79.9%79.7%
MMMU-Pro (Vals)Vals AI88.3%–
MortgageTaxVals AI68.8%–
SAGEVals AI–83.4%
Blueprint-Bench 2Epoch AI Benchmarking Hub36.2%†31.2%†
Code2Video-AAArtificial Analysis10001030
AA-3DArtificial Analysis–1000
Long context
AA-LCR v1.1Artificial Analysis84.3%83.3%
Arena DocumentArena (LMArena)1479†–
MLCRArtificial Analysis28.9%26.1%
Composite
Epoch Capabilities IndexEpoch AI Benchmarking Hub160.0†156.7†
LiveBench 2.0LiveBench–60.4%†
LiveBench 1.0LiveBench80.2%72.0%
AA Intelligence Index v5.0Artificial Analysis–27.9
AA Intelligence Index v4.3.2Artificial Analysis38.438.1
AA Progress Index v1Artificial Analysis320317.1
Vals IndexVals AI–52.3
Vals Finance IndexVals AI–53.0%
Vals RSI IndexVals AI16.5%–
Vals Science IndexVals AI–28.4%
Vals Multimodal IndexVals AI68.1%–
Vals Router IndexVals AI–52.3%†
AA Cyber IndexArtificial Analysis–52.7
Safety & honesty
FORTRESSScale AI SEAL16.3%10.8%†

Data as of 2026-11-09. Best configuration of each model; every score links to its source on the model pages.

DuelLab GameBench 2, release gb2-20261103-eaea31df94e6 (https://benchmarks.duellab.org/releases/gb2-20261103-eaea31df94e6/), CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Scores mapped to BenchLeader model names; not endorsed by DuelLab.

What changed

  • GPT-6 Luna (max): 1 score revision.
  • GPT-6 Luna (max): 1 score revision.
  • GPT-5.5 (xhigh): 1 score revision.
  • GPT-6 Luna (max): 1 score revision.
  • GPT-6 Luna (max): 1 score revision.
  • GPT-6 Luna (max): 1 new result (MirrorCode); 2 score revisions.
  • GPT-6 Luna (max): BenchLeader Index 58.6 → 56.6.
  • GPT-5.5 (xhigh): 1 new result (AA Progress Index v1).
  • GPT-6 Luna (max): 5 new results (AA Intelligence Index v5.0, AA Progress Index v1, HLE-Diamond (AA)…); 4 score revisions; cost per task moved from $0.068/M to $0.15/M (124% up).
  • GPT-5.5 (xhigh): cost per task moved from $2.63/M to $2.10/M (20% down).

Rankings: Best LLM overall · Best LLM for agents · Best cheap LLMs

GPT-5.5 vs GPT-6 Luna: questions

Is GPT-5.5 better than GPT-6 Luna?
GPT-5.5 (xhigh) leads on quality: 64.3 vs 56.5. The BenchLeader Index combines every independent quality benchmark; GPT-5.5 (xhigh) is ahead overall as of 9 Nov 2026, but check the category scores for your use.
GPT-5.5 vs GPT-6 Luna: which is cheaper, and will that change?
GPT-6 Luna is cheaper today: $0.200 against $11.25 per million tokens, blended at three input tokens per output token. No price change has been announced for either.
Is GPT-5.5 or GPT-6 Luna better for coding?
GPT-5.5 scores higher in coding (61 vs 58 on the category index, where 50 is average). On Arena WebDev, the top shared coding benchmark, it is 1512 for GPT-5.5 against 1577 for GPT-6 Luna.
Which is faster, GPT-5.5 or GPT-6 Luna?
GPT-6 Luna streams faster (104 vs 80 output tokens per second, Artificial Analysis 7-day median).
Is GPT-5.5 or GPT-6 Luna better for agents and tool use?
GPT-5.5 scores higher in agentic tasks (62 vs 49 on the category index, where 50 is average).
More questions (4)
Which is better for long documents?
They are level on long-context benchmarks (67 vs 66). Both accept 1,050,000 tokens of context.
Which has lower latency?
GPT-5.5 answers first: 44.1 s against 85.0 s to the first answer token, as Artificial Analysis measures it. Reasoning effort drives most of this: a higher setting thinks longer before it answers.
Do independent benchmarks agree on GPT-5.5 vs GPT-6 Luna?
Across the 44 benchmarks both have, GPT-5.5 leads 36, GPT-6 Luna leads 7 and 1 is a tie. Every overall index that rates both puts GPT-5.5 ahead.
When was GPT-6 Luna released?
GPT-6 Luna was released on 22 Sep 2026.