GPT-5.6 Luna
OpenAI · Released Jun 2026
OpenAI's budget GPT-5.6 tier — TerminalBench 2.1 at 82.5% for $1/$6 per 1M tokens, undercutting Claude Haiku 4.5 and Gemini Flash on capability-per-dollar. The caveat: Luna is government-gated to ~20 trusted partners, with no independent verification or GA date. Best for teams building model-routing architectures who can escalate cheap failures to Terra or Sol.
Is it right for you?
Good for
- Best capability-per-dollar in the GPT-5.6 family: TerminalBench 2.1 at 82.5% is only 0.9 points behind GPT-5.5 (83.4%) at 1/5 Sol's cost. For high-volume agentic workflows, Luna is the economics winner.
- Speed and throughput: positioned as the fastest GPT-5.6 model, optimized for latency-sensitive products, agent swarms, customer support, and real-time classification pipelines.
- Routine automation and extraction: classification, summarization, formatting, routing, draft generation, and background automation where cost-per-request and throughput dominate over raw reasoning depth.
- Model-routing architectures: the bottom tier of a Sol > Terra > Luna escalation ladder. Use Luna by default, escalate to Terra or Sol when Luna's eval score drops below threshold on a specific task.
Not good for
- Government-gated with no public access: same limited preview restriction. Luna's value proposition is clear on paper, but no independent verification exists.
- CTF score of 85.19% is the lowest in the family — solid but not dominant. For security-critical workflows, Terra or Sol are the appropriate tier.
- Lacks the safety depth of Sol and Terra: no activation classifiers on Luna (per system card). For regulated cyber and bio workflows, use Terra or Sol with full monitoring stack.
- At $1/$6, Luna is competitive but not the cheapest model on the market — GLM-5.2 ($1.40/$4.40) and DeepSeek V4 Pro ($0.44/$0.87) offer lower output pricing for similar capability tiers.
How it performs by task
High-volume agentic coding (budget)
82.5% on TerminalBench 2.1 is only 0.9 behind GPT-5.5. Remarkable for a budget tier. Route routine coding tasks to Luna, escalate complex ones.
Classification and extraction
The ideal model for cheap, high-throughput tasks. Classification, entity extraction, sentiment, routing, and formatting at $1/$6 is the economics win of the GPT-5.6 family.
Summarization and drafting
Fast and affordable for document summarization, email drafting, report generation, and content workflows where speed matters more than extreme precision.
Cybersecurity
CTF 85.19% is solid for a budget model but trails Terra (91.84%) and Sol (96.7%). No activation classifiers. Not the right tier for security-critical work.
Hard reasoning and deep research
Budget tier with no max or ultra reasoning modes. For hard problems, route to Sol. For everyday reasoning, Terra. Luna is for volume, not depth.
Pricing
Input
$1 / 1M tokens
Output
$6 / 1M tokens
Context
Fastest and most cost-efficient GPT-5.6 tier.
Benchmarks
Verdict history
Sources
Verification log
- Pricing— No changes
Automated agent
- Pricing— No changes
Automated agent
- Status— Updated
Automated agent
Summary re-dated to Jul 7 2026 and made explicit about what is awaited: stays pending pending GA + independent benchmarks; still government-gated (~20 orgs); family trending toward release (~Jul 9 GA per prediction markets, unconfirmed). Verdict unchanged (pending).
- Pricing— No changes
Automated agent
- Pricing— No changes
Automated agent
Pricing unchanged: $1/$6 per 1M tokens. Government-gated. Confirmed by OpenAI blog.
- Profile— No changes
Imported at launch
- Pricing— No changes
Imported at launch