GPT-5.6 Luna
GPT-5.6 Luna is an API-only (closed weights) language model from OpenAI, released July 9, 2026. The context window is 1.1M tokens. On the Epoch Capabilities Index it scores 156.7, rank 35 of 256 rated models. API price: $0.2 input / $1.2 output per million tokens.
Check it against your own PC →
Lab
OpenAI
Released
July 9, 2026
Weights
API-only (closed weights)
Parameters
–
Context
1.1M
Price / M tokens
$0.2 / $1.2 in / out
Epoch ECI
156.7 #35
Strengths by category
ModelTape's 0–100 fit on Epoch AI benchmark results.
| Category | Score | Based on |
|---|---|---|
| Reasoning | 15.6 | Chess Puzzles, SimpleBench, Mystery Game Puzzles |
| Math | 65.5 | ProofBench, OTIS Mock AIME 2024-2025, FrontierMath-Tiers-1-3-v2-Private, FrontierMath-Tier-4-v2-Private |
| Coding | 52.8 | MirrorCode, DeepSWE |
| Knowledge | 73.8 | GPQA diamond, SimpleQA Verified |
Benchmark results
| Benchmark (Epoch AI) | Score |
|---|---|
| OTIS Mock AIME | 98.3% |
| GPQA Diamond | 92.5% |
| FrontierMath (Tiers 1–3) | 86.4% |
| DeepSWE | 67.2% |
| FrontierMath-Tier-4-v2-Private | 61.0% |
| ProofBench | 60.0% |
| Balrog | 45.6% |
| SimpleQA Verified | 41.0% |
| Chess Puzzles | 40.0% |
| SimpleBench | 36.2% |
| MirrorCode | 21.1% |
| Furniture Assembly | 17.9% |
| Mystery Game Puzzles | 13.0% |
Links
Announcement · Epoch AI benchmarks
Models with a similar score
Claude Haiku 5.5 · 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
More from OpenAI
GPT-6.1 Terra · GPT-6.1 Sol · GPT-6 Sol · GPT-6 Luna · GPT-6 Astra · GPT-5.6 Cyber · Daybreak Red · Daybreak Blue