GPT-5 vs GPT-6 Luna
| Spec | GPT-5 | GPT-6 Luna |
|---|---|---|
| Respan Index | 39.6 (#61) | 49.1 (#37) |
| Blended price per 1M | $3.44 | $0.1 |
| Context window | 400K | 1.1M |
| Input / output per 1M | $1.25 / $10 | $0.05 / $0.25 |
| Max output | 128K | 128K |
| Input | text, vision | text, vision |
| Released | 2025-08-07 | 2026-09-22 |
Respan Index by category
Each category is scored 0 to 100, and how far ahead the winner is. Leads under a point are close to even.
| Category | GPT-5 | GPT-6 Luna |
|---|---|---|
| Coding | 11.3 GPT-5 | 29.6 GPT-6 Luna |
| Agents | 54.3 GPT-5 | 61.1 GPT-6 Luna |
| Reasoning | 42.2 GPT-5 | 57.0 GPT-6 Luna |
| Knowledge & language | 50.0 GPT-5 | 38.9 GPT-6 Luna |
| Human preference | 50.9 GPT-5 | 55.2 GPT-6 Luna |
Benchmarks both report
GPT-6 Luna leads on 9 of the 12 benchmarks both report. Higher is better. Each score links to where it was published.
| Benchmark | GPT-5 | GPT-6 Luna |
|---|---|---|
| MirrorCode (Epoch AI) | 4.4% | 26.7% |
| Chess Puzzles (Epoch AI) | 36% | 36% |
| LMArena Elo | 1435 | 1441 |
| LMArena WebDev (LMArena) | 1417 | 1579 |
| LMArena Vision (LMArena) | 1211 | 1240 |
| FrontierMath Tier 4 v2 (Epoch AI) | 22% | 56.1% |
| FrontierMath Tiers 1-3 v2 (Epoch AI) | 55.4% | 78.9% |
| GPQA Diamond | 86.2% | 90.5% |
| Mystery Game Puzzles (Epoch AI) | 23% | 7% |
| OTIS Mock AIME 2024-2025 (Epoch AI) | 91.4% | 98.9% |
| SAGE (Vals AI) | 43.7% | 48.1% |
| SimpleQA Verified | 50.1% | 41.4% |
FAQ
Is GPT-5 better than GPT-6 Luna?
GPT-6 Luna scores 49.1 on the Respan Index (#37), ahead of GPT-5 at 39.6 (#61). GPT-6 Luna leads on 9 of the 12 benchmarks both report.
Which is cheaper, GPT-5 or GPT-6 Luna?
GPT-5 lists at $1.25 input and $10 output per 1M tokens; GPT-6 Luna at $0.05 and $0.25. GPT-6 Luna is 34x cheaper per token at list price.
Which has the larger context window?
GPT-5 accepts 400K tokens and GPT-6 Luna 1.1M tokens.