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GPT-5.5 vs GPT-5.6 Luna Pro
GPT-5.5 (OpenAI) and GPT-5.6 Luna Pro (OpenAI) compared on benchmarks, pricing, context window, and use-case rankings.
- GPT-5.6 Luna Pro is cheaper on input tokens — $1.00 vs $5.00 per 1M.
| Attribute | GPT-5.5 | GPT-5.6 Luna Pro |
|---|---|---|
| Scores | ||
| Intelligence (ECI) | 159 | — |
| Coding | 91 | — |
| Math | 97 | — |
| Reasoning & Knowledge | 92 | — |
| Agentic & Tools | 88 | — |
| Specifications | ||
| Developer | OpenAI | OpenAI |
| Family | GPT | GPT |
| Released | Apr 23, 2026 | Jul 9, 2026 |
| Parameters | — | — |
| Availability | API access | — |
| Context window | 1.1M | 1.1M |
| Price — $/M input | $5.00 | $1.00 |
| Price — $/M output | $30.00 | $6.00 |
| Inputs | file, image, text | file, image, text |
| Outputs | text | text |
| Benchmarks | ||
| AIME 2024/2025 | 100% | — |
| APEX | 38% | — |
| ARC-AGI | 95% | — |
| ARC-AGI-2 | 85% | — |
| FrontierMath | 52% | — |
| FrontierMath Tier 4 | 35% | — |
| GPQA Diamond | 94% | — |
| GSO (code optimization) | 40% | — |
| Humanity's Last Exam | 44% | — |
| SciCode | 56% | — |
| SimpleBench | 69% | — |
| SimpleQA Verified | 63% | — |
| SWE-bench Verified | 81% | — |
| Terminal-Bench | 85% | — |
| WebDev Arena | 1505 | — |
| WeirdML | 85% | — |
| τ²-bench | 94% | — |
Use-case scores are 0–100 percentile composites across each area’s benchmarks, ranked against every model from the past year. Highlighted cells lead each row. Open a model for the full picture.
Frequently asked questions
Which is cheaper, GPT-5.5 or GPT-5.6 Luna Pro?
GPT-5.6 Luna Pro is cheaper on input tokens at $1.00 per million, versus $5.00 (representative OpenRouter pricing).
Which has a larger context window, GPT-5.5 or GPT-5.6 Luna Pro?
GPT-5.5 supports up to 1.1M tokens, compared with 1.1M for the other.
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Benchmarks & model data from Epoch AI (CC BY); pricing & specs from OpenRouter. ECI = Epoch Capabilities Index.