GPT-6 Luna
GPT-6 Luna is an API-only (closed weights) language model from OpenAI, released September 22, 2026. The context window is 1.1M tokens. On the Epoch Capabilities Index it scores 156.4, rank 36 of 256 rated models. API price: $0.1 input / $0.5 output per million tokens.
Earlier this month, we introduced GPT‑6 Astra, the most intelligent and aligned model in the world. While the most demanding and important projects still call for Astra’s full depth, work happens at different scales, rhythms, and budgets. That’s why we’re expanding the GPT‑6 universe with GPT‑6 Sol and GPT‑6 Luna.
Check it against your own PC →
Strengths by category
ModelTape's 0–100 fit on Epoch AI benchmark results.
| Category | Score | Based on |
|---|---|---|
| Reasoning | 16.4 | Chess Puzzles, Mystery Game Puzzles |
| Math | 64.7 | ProofBench, OTIS Mock AIME 2024-2025, FrontierMath-Tiers-1-3-v2-Private, FrontierMath-Tier-4-v2-Private |
| Knowledge | 73.4 | GPQA diamond, SimpleQA Verified |
Benchmark results
| Benchmark (Epoch AI) | Score |
|---|---|
| OTIS Mock AIME | 98.9% |
| GPQA Diamond | 90.9% |
| FrontierMath (Tiers 1–3) | 83.1% |
| ProofBench | 64.0% |
| FrontierMath-Tier-4-v2-Private | 56.1% |
| SimpleQA Verified | 41.4% |
| Chess Puzzles | 32.7% |
| MirrorCode | 26.7% |
| Furniture Assembly | 20.2% |
| Mystery Game Puzzles | 0.0% |
| SpireClimb | 0.0% |
Links
Announcement · Epoch AI benchmarks
Models with a similar score
GPT-5.4 Pro · GPT-5.5 · Claude Opus 4.8 · DeepSeek V4.1 Flash 1017 · Gemini 3.8 Flash · Kimi K3 · Gemini 3.7 Flash · Muse Spark 1.3
More from OpenAI
GPT-6.1 Terra · GPT-6.1 Sol · GPT-6 Sol · GPT-6 Astra · GPT-5.6 Cyber · Daybreak Red · Daybreak Blue · GPT-5.6 Sol