The Right-Sized LLM Benchmark Cheapest LLM that's good enough.

GPT-5.6 Luna at a glance

Good enough on 25/52 tasks at the 90% bar. Best value on 2 tasks. Best fit for: Structured Data & Fact Extraction, Content Summarization & Synthesis, Long-form Content Generation.

Provider
OpenAI
Model name
gpt-5.6-luna
Cost mode:
Qualifies on
25 / 52 tasks (at 90% bar)
Best value on
2 tasks

Cost vs quality across all tasks

0%25%50%75%100%78910Quality score (7–10)Cost-efficiency vs best value (1.0 = best value)Content Summarization — quality 9.11, 7.7x the cost of the best-value good-enough optionResearch Query Generation — quality 7.94, this model IS the best-value good-enough option★Theme Generation — quality 9.12, 2.0x the cost of the best-value good-enough optionStructured Output Extraction — quality 9.51, 30.3x the cost of the best-value good-enough optionActivity Feed Blurb Generation — quality 8.36, 2.8x the cost of the best-value good-enough optionResearch Query Validation — quality 7.92, 1.8x the cost of the best-value good-enough optionSubstack Newsletter — quality 8.46, 5.1x the cost of the best-value good-enough optionGeographic Region Identification — quality 8.74, this model IS the best-value good-enough option★Social Post Promotion — quality 8.53, 3.0x the cost of the best-value good-enough optionSubreddit Quality Vetting — quality 9.48, 2.5x the cost of the best-value good-enough optionLanguage Detection — quality 9.95, 7.2x the cost of the best-value good-enough optionExecutive Summary Generation — quality 7.66, 3.6x the cost of the best-value good-enough optionLanding Page Section Generation — quality 9.62, 2.0x the cost of the best-value good-enough optionTopic Cluster Naming — quality 8.43, 1.8x the cost of the best-value good-enough optionTopic Grouping and Client Matching — quality 8.00, 2.7x the cost of the best-value good-enough optionEngagement Triage — quality 8.64, 8.1x the cost of the best-value good-enough optionPrompt Adaptation — quality 8.48, 4.3x the cost of the best-value good-enough optionOnboarding Chapter Outline Generation — quality 9.32, 4.6x the cost of the best-value good-enough optionX Post Selection — quality 8.41, 5.1x the cost of the best-value good-enough optionClaim Extraction — quality 7.32, 7.3x the cost of the best-value good-enough optionAuthor Voice Generation — quality 9.02, 4.7x the cost of the best-value good-enough optionSEC S-1 Chunk Analysis — quality 8.86, 2.5x the cost of the best-value good-enough optionClaim Refinement — quality 7.90, 5.2x the cost of the best-value good-enough optionImage Prompt Generation — quality 9.02, 6.5x the cost of the best-value good-enough optionEngagement Reply Draft — quality 8.21, 1.7x the cost of the best-value good-enough option

within ~1.3× of the best-value model · 1.3–2× · >2× · ★ this model is the best-value pick on that task. Top-right = best quadrant. Only tasks where this model qualifies at the 90% bar are plotted.

Per-task breakdown

TaskCategoryQuality (% of best)ConfidenceOverpay
Geographic Region Identification ★Structured Data & Fact Extraction93%HIGHbest value
Research Query Generation ★Infrastructure & Utility93%HIGHbest value
Engagement Reply DraftSocial & Promotional Content97%RANKED1.7x
Research Query ValidationInfrastructure & Utility92%MEDIUM1.8x
Topic Cluster NamingTopic Organization & Clustering96%HIGH1.8x
Landing Page Section GenerationLong-form Content Generation98%MEDIUM2x
Theme GenerationLong-form Content Generation94%HIGH2x
SEC S-1 Chunk AnalysisFinancial Analysis & Trading Decisions96%HIGH2.5x
Subreddit Quality Vetting bestRelevance, Classification & Matching100%MEDIUM2.5x
Topic Grouping and Client MatchingRelevance, Classification & Matching93%MEDIUM2.7x
Activity Feed Blurb GenerationSocial & Promotional Content95%RANKED2.8x
Social Post PromotionSocial & Promotional Content96%RANKED3x
Executive Summary GenerationContent Summarization & Synthesis97%MEDIUM3.6x
Prompt AdaptationInfrastructure & Utility95%RANKED4.3x
Onboarding Chapter Outline GenerationLong-form Content Generation95%RANKED4.6x
Author Voice GenerationLong-form Content Generation93%RANKED4.7x
Substack NewsletterLong-form Content Generation91%RANKED5.1x
X Post SelectionRelevance, Classification & Matching96%HIGH5.1x
Claim RefinementInfrastructure & Utility93%MEDIUM5.2x
Image Prompt GenerationInfrastructure & Utility98%RANKED6.5x
Language DetectionRelevance, Classification & Matching99%RANKED7.2x
Claim ExtractionStructured Data & Fact Extraction93%MEDIUM7.3x
Content SummarizationContent Summarization & Synthesis96%HIGH7.7x
Engagement TriageRelevance, Classification & Matching97%HIGH8.1x
Structured Output ExtractionStructured Data & Fact Extraction97%HIGH30x

Overpay — how much more you pay by running this model instead of the best-value model that clears the quality bar on that task (marked ★). "16x" means you overpay 16× — the same output for 16× the best-value good-enough option; ★ means this model is that option (no overpayment). Confidence — how sure we are about the quality score (more judgments + more agreement = higher confidence): RANKED many independent judges scored this model's outputs and their agreement is very high (most confident) — HIGH many judges have scored it and they mostly agree (well-pinned) — MEDIUM enough judges have weighed in to publish, but they disagree more than we'd like (treat with a small grain of salt). LOW-confidence cells are hidden everywhere on the site. See the methodology for the exact thresholds.