GPT-5.5 Pro vs GPT-6 Astra
GPT-5.5 Pro (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 162).
- GPT-6 Astra is cheaper on input tokens — $10.00 vs $30.00 per 1M.
| Attribute | GPT-5.5 Pro | GPT-6 Astra |
|---|---|---|
| Scores | ||
| Intelligence (ECI) | 162 | 169 |
| Coding | — | 95 |
| Math | 99 | 96 |
| Reasoning & Knowledge | 87 | 99 |
| Agentic & Tools | — | 96 |
| Specifications | ||
| Developer | OpenAI | OpenAI |
| Family | GPT | GPT |
| Released | Apr 23, 2026 | Sep 3, 2026 |
| Parameters | — | — |
| Availability | API access | API access |
| Context window | 1.1M | 1.1M |
| Price — $/M input | $30.00 | $10.00 |
| Price — $/M output | $180.00 | $50.00 |
| Inputs | file, image, text | file, image, text |
| Outputs | text | text |
| Benchmarks | ||
| AIME 2024/2025 | 100% | 100% |
| ARC-AGI | 97% | 99% |
| ARC-AGI-2 | 85% | 95% |
| FrontierMath | 52% | — |
| FrontierMath Tier 4 | 40% | — |
| GPQA Diamond | 94% | 96% |
| SimpleBench | 77% | — |
| SimpleQA Verified | 65% | 76% |
| APEX | — | 47% |
| Humanity's Last Exam | — | 55% |
| SciCode | — | 56% |
| WebDev Arena | — | 1797 |
| WeirdML | — | 93% |
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-5.5 Pro better than GPT-6 Astra?
On Epoch AI's Capabilities Index, GPT-6 Astra scores higher (169) than GPT-5.5 Pro (162). The right pick depends on your task — compare their coding, math, and reasoning scores in the table above.
Which is cheaper, GPT-5.5 Pro or GPT-6 Astra?
GPT-6 Astra is cheaper on input tokens at $10.00 per million, versus $30.00 (representative OpenRouter pricing).
Which has a larger context window, GPT-5.5 Pro or GPT-6 Astra?
GPT-5.5 Pro supports up to 1.1M tokens, compared with 1.1M for the other.
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More comparisons
Benchmarks & model data from Epoch AI (CC BY); pricing & specs from OpenRouter. ECI = Epoch Capabilities Index.