GPT-5.5 vs GPT-5.6 Luna
Price, context window & benchmark comparison
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Verdict: GPT-5.6 Luna is 25.0× cheaper than GPT-5.5 on a typical 3:1 input/output mix. GPT-5.5 scores higher on the Artificial Analysis Intelligence Index (38.4 vs 37.3).
| GPT-5.5 | GPT-5.6 Luna | |
|---|---|---|
| Input price / 1M | $5.00 | $0.20 |
| Output price / 1M | $30.00 | $1.20 |
| Blended price (3:1) | $11.25 | $0.45 |
| Cached input / 1M | $0.50 | $0.02 |
| Context window | 1.1M | 1.1M |
| Max output | 128K | 128K |
| Intelligence index | 38.4 | 37.3 |
| Coding index | 74.9 | 71.4 |
| Providers | — | 7 |
| Best provider uptime (30m) | — | 100.0% |
| Vision input | Yes | Yes |
| Reasoning | Yes | Yes |
| Tool calling | Yes | Yes |
| Released | 2026-04-24 | 2026-07-09 |
| Retirement | — | — |
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FAQ
Which is cheaper, GPT-5.5 or GPT-5.6 Luna?
GPT-5.6 Luna is 25.0× cheaper than GPT-5.5 on a typical 3:1 input/output mix.
GPT-5.5 vs GPT-5.6 Luna: which has a bigger context window?
GPT-5.5: 1,050,000 tokens. GPT-5.6 Luna: 1,050,000 tokens.
How much would 1 million requests cost?
At 2,000 input + 500 output tokens per request: GPT-5.5 ≈ $25,000, GPT-5.6 Luna ≈ $1,000.
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