Compare / head-to-head
GPT-5.5 ProvsGPT-5.6 Luna
GPT-5.5 Pro leads 2 of 2 shared benchmarks. GPT-5.6 Luna is 150x cheaper per token. Both offer a 1.1M-token context window.
Benchmarks from cited public sources; pricing from official pages; status from official provider feeds.
Shared benchmarks
2 – 0
GPT-5.5 Pro leads
Cheaper per token
GPT-5.6 Luna
150x cheaper, input + output
Larger context
Tie
both 1.1M tokens
Provider uptime (30d)
94.3463%
OpenAI
GPT-5.5 Pro
OpenAI · released 2026-04-23
textvision
GPT-5.6 Luna
OpenAI · released 2026-07-09
textvision
Quality
Benchmark matrix
2 shared · 6 only GPT-5.5 Pro · 5 only GPT-5.6 Luna| Benchmark | GPT-5.5 Pro | GPT-5.6 Luna | Δ | Edge |
|---|---|---|---|---|
| Reported by both · 2 | ||||
| FrontierMath Tier 4 v2 (Epoch AI run) | 78% ↗epoch | 61% ↗epoch | +17 pt | GPT-5.5 Pro |
| FrontierMath Tiers 1-3 v2 (Epoch AI run) | 87.7% ↗epoch | 82.1% ↗epoch | +5.6 pt | GPT-5.5 Pro |
| Only GPT-5.5 Pro reports · 6 | ||||
| Humanity's Last Exam (no tools) | 43.1% ↗ | not reported | — | — |
| BrowseComp | 90.1% ↗ | not reported | — | — |
| FrontierMath Tier 1-3 | 52.4% ↗ | not reported | — | — |
| FrontierMath Tier 4 | 39.6% ↗ | not reported | — | — |
| GDPval (wins or ties) | 82.3% ↗ | not reported | — | — |
| Humanity's Last Exam (with tools) | 57.2% ↗ | not reported | — | — |
| Only GPT-5.6 Luna reports · 5 | ||||
| GPQA Diamond | not reported | 92.3% ↗ | — | — |
| DeepSWE v1.1 | not reported | 67.2% ↗ | — | — |
| OTIS Mock AIME 2024-2025 (Epoch AI run) | not reported | 98.3% ↗epoch | — | — |
| SimpleQA Verified | not reported | 41% ↗epoch | — | — |
| SWE-Bench Pro | not reported | 62.7% ↗ | — | — |
Scores tagged "epoch" or "matharena" are independent runs, used only where the lab has not published its own; ⚠ marks rows MathArena flags as released after the competition. Higher is better on every row. Δ is GPT-5.5 Pro minus GPT-5.6 Luna in the benchmark's own unit. "Not reported" means the lab has not published that figure; it is not a zero. ↗ opens the source.
Specs & pricing
Side by side
Official pricing pages and model cards| Spec | GPT-5.5 Pro | GPT-5.6 Luna | Edge |
|---|---|---|---|
| Context window | 1.1M tokens | 1.1M tokens | Tie |
| Max output | 128K tokens | 128K tokens | Tie |
| Input price / 1M | $30 ↗ | $0.2 ↗ | GPT-5.6 Luna |
| Output price / 1M | $180 ↗ | $1.2 ↗ | GPT-5.6 Luna |
| Cached input / 1M | — | $0.02 ↗ | — |
| Input + output / 1M Lower is cheaper. List prices; batch, tool and regional fees excluded. | $210 | $1.4 | GPT-5.6 Luna |
| Modalities | text · vision | text · vision | Tie |
| Released | 2026-04-23 | 2026-07-09 | — |
| Cited benchmark scores | 8 | 8 | — |
Reliability
OpenAI status
Last 60 days · refreshed daily on this page · live on /statusMore matchups
GPT-5.5 Pro vs …
Models sharing the most benchmarksMore matchups
GPT-5.6 Luna vs …
Models sharing the most benchmarksBuilt by Respan
Which one wins on your data?
Public benchmarks are a starting point. Run GPT-5.5 Pro and GPT-5.6 Luna on your own prompts with Respan evals, or route to either through one gateway key with automatic failover.