GPT-5.6 Luna vs GPT-6 Astra
GPT-5.6 Luna (OpenAI) and GPT-6 Astra (OpenAI) compared on benchmarks, pricing, context window, and use-case rankings.
- GPT-6 Astra leads on overall intelligence (ECI 169 vs 156).
- GPT-5.6 Luna is cheaper on input tokens — $0.20 vs $10.00 per 1M.
- GPT-6 Astra ranks higher for coding (93th vs 69th percentile).
| Attribute | GPT-5.6 Luna | GPT-6 Astra |
|---|---|---|
| Scores | ||
| Intelligence (ECI) | 156 | 169 |
| Coding | 69 | 93 |
| Math | 80 | 91 |
| Reasoning & Knowledge | 49 | 98 |
| Agentic & Tools | 51 | 90 |
| Specifications | ||
| Developer | OpenAI | OpenAI |
| Family | GPT | GPT |
| Released | Jul 9, 2026 | Sep 3, 2026 |
| Parameters | — | — |
| Availability | API access | API access |
| Context window | 1.1M | 1.1M |
| Price — $/M input | $0.20 | $10.00 |
| Price — $/M output | $1.20 | $50.00 |
| Inputs | file, image, text | file, image, text |
| Outputs | text | text |
| Benchmarks | ||
| AIME 2024/2025 | 98% | 100% |
| APEX | 43% | 65% |
| ARC-AGI | 88% | 99% |
| ARC-AGI-2 | 60% | 95% |
| GPQA Diamond | 92% | 96% |
| Humanity's Last Exam | 40% | 55% |
| SciCode | 54% | 56% |
| SimpleBench | 47% | — |
| SimpleQA Verified | 41% | 76% |
| WebDev Arena | 1519 | 1800 |
| WeirdML | 61% | 94% |
| GSO (code optimization) | — | 79% |
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
Is GPT-5.6 Luna better than GPT-6 Astra?
On Epoch AI's Capabilities Index, GPT-6 Astra scores higher (169) than GPT-5.6 Luna (156). The right pick depends on your task — compare their coding, math, and reasoning scores in the table above.
Which is cheaper, GPT-5.6 Luna or GPT-6 Astra?
GPT-5.6 Luna is cheaper on input tokens at $0.20 per million, versus $10.00 (representative OpenRouter pricing).
Which has a larger context window, GPT-5.6 Luna or GPT-6 Astra?
GPT-5.6 Luna supports up to 1.1M tokens, compared with 1.1M for the other.
Which is better for coding, GPT-5.6 Luna or GPT-6 Astra?
Across coding benchmarks like SWE-bench Verified and Terminal-Bench, GPT-6 Astra ranks higher — 93th vs 69th percentile among the models tracked on Model Beat.
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Benchmarks & model data from Epoch AI (CC BY); pricing & specs from OpenRouter. ECI = Epoch Capabilities Index.