GPT-5.5 vs GPT-5.6 Luna
Price, context and benchmark scores side by side — every number from the live model catalogue.
| GPT-5.5openai | GPT-5.6 Lunaopenai | |
|---|---|---|
| Input / 1M tokens | $5.00 | $0.500 |
| Output / 1M tokens | $30.00 | $3.00 |
| 1M in + 300K out | $14.00 | $1.40 |
| Context window | 1.1M | 1.1M |
| Intelligence index | 54.8 | 51.2 |
| Coding index | 74.9 | 71.4 |
| Agentic index | 44.9 | 45.6 |
| Cheapest provider | Azure | OpenAI |
| Providers serving it | 2 | 2 |
| Weights | Closed | Closed |
| Image input | Yes | Yes |
| Tool calling | Yes | Yes |
| Reasoning mode | Yes | Yes |
| Released | Apr 24, 2026 | Jul 9, 2026 |
Which one to pick
Pick GPT-5.5 if…
- You want the higher general-intelligence score (54.8).
- Code quality is the priority — it leads on the coding index (74.9).
Pick GPT-5.6 Luna if…
- You are running agent loops — higher agentic index (45.6).
- Token cost matters: $3.00 per 1M output vs $30.00.
- You need the bigger context window (1.1M).
FAQ
Is GPT-5.5 better than GPT-5.6 Luna?
GPT-5.5 scores higher on general intelligence (54.8 vs 51.2), while GPT-5.6 Luna is 10× cheaper per output token ($3.00 vs $30.00). For code, GPT-5.5 leads (74.9 coding index). GPT-5.6 Luna takes the larger context at 1.1M.
Which is cheaper, GPT-5.5 or GPT-5.6 Luna?
GPT-5.6 Luna, at $3.00 per 1M output tokens versus $30.00. On a 1M input + 300K output workload that is $1.40 against $14.00.
Can I self-host GPT-5.5 or GPT-5.6 Luna?
GPT-5.5: closed weights, API only. GPT-5.6 Luna: closed weights, API only.