GPT-5.6 Luna by OpenAI is a high-volume reasoning model with a 1,050,000 context window, 128K max output, text and image input, and nano-tier positioning.
Capabilities, design details, and architectural traits
GPT 5.6 Luna is the high-volume tier of the GPT 5.6 family, positioned for high-volume workloads. It roughly corresponds to the nano model tier used in earlier GPT 5 generations, offering High reasoning and Fast speed.
| Trait | Detail |
|---|---|
| Tier positioning | Designed for high-volume workloads; roughly corresponds to the nano model tier from earlier GPT 5 families |
| Context window | 1,050,000 input tokens with 128,000 max output tokens |
| Modality constraints | Text and image input only, text output only; audio and video are not supported |
| Fine-tuning | Not supported |
| Tool ecosystem | Web search, file search, code interpreter, hosted shell, computer use, MCP, tool search, skills, apply patch, and image generation |
Luna accepts text and image input but produces text-only output, and it drops audio and video support entirely. Unlike many models in the GPT 5.6 lineup, fine-tuning is not available, so customization relies on prompting and the built-in tool ecosystem rather than weight updates.
Independent evaluations · Artificial Analysis
Evaluate specifications, pricing, and independent benchmark indices
| Model Details | |||
|---|---|---|---|
| General Info | |||
| Provider | OpenAI | Anthropic | Anthropic |
| Release Date | July 9, 2026 | July 24, 2026 | June 9, 2026 |
| Knowledge Cutoff | Feb 2026 | May 2026 | - |
| Context & Limits | |||
| Context Window | 1.1M Best Context Window | 1M | 1M |
| Pricing (per 1M tokens) | |||
| Input Pricing | $0.20 Best Input Pricing | $5 | $10 |
| Output Pricing | $1.20 Best Output Pricing | $25 | $50 |
| Modalities | |||
| Inputs | textimage | textimage | textimagefile |
| Outputs | text | text | text |
| Benchmarks (0-100) | |||
| Intelligence Index | 52.3 | 63.1 Best Intelligence Index | 62.1 |
| Coding Index | 71.4 | 78.0 Best Coding Index | 76.5 |
| Agentic Index | 46.9 | 59.2 Best Agentic Index | 56.6 |
Graduate-level reasoning and expert Q&A evaluation.
Extremely difficult logical reasoning and knowledge.
Logical reasoning over long context windows.
Independent evaluation data provided by Artificial Analysis. To view the latest benchmarks and full details, visit their official site.
