Claude Opus 5.5 vs GPT-6 Astra: Specs & Benchmark Comparison
Claude Opus 5.5 is developed by Anthropic, while GPT-6 Astra comes from OpenAI. Both were released in September 2026.
The two models share 9 published benchmarks. Claude Opus 5.5 leads on 7 of them, GPT-6 Astra on 2. The widest gaps are on Humanity's Last Exam (with tools, text-only), where Claude Opus 5.5 scores 67.7% against 57.2%; OSWorld 2.0, where Claude Opus 5.5 scores 81.8% against 72.6%. Averaged across everything we track, Claude Opus 5.5 sits at 71.1% and GPT-6 Astra at 74.4%.
Claude Opus 5.5 is the cheaper API at $4 per million input tokens and $20 per million output tokens, roughly 3 times cheaper than GPT-6 Astra at $10 and $50. Both accept a context window of about 1M tokens. Both accept text and images as input.
| Characteristic | Claude Opus 5.5 | GPT-6 Astra |
|---|---|---|
| Company | Anthropic | OpenAI |
| Release Date | September 22, 2026 | September 4, 2026 |
| Parameters | — | — |
| Multimodal | Yes | Yes |
| Context (input) | 1.0M | 1.1M |
| Context (output) | 128K | 128K |
| Input Price / 1M | $4.00 | $10.00 |
| Output Price / 1M | $20.00 | $50.00 |
| Average Score | 71.1% | 74.4% |
| Benchmarks | ||
| Humanity's Last Exam (with tools, text-only) | 67.7% | 57.2% |
| OSWorld 2.0 | 81.8% | 72.6% |
| Terminal-Bench 4.0 | 66.4% | 57.7% |
| Terminal-Bench-Science 0.1 | 58.7% | 64.6% |
| HealthBench Professional | 65.6% | 63.4% |
| AutomationBench | 40.0% | 41.4% |
| FrontierCode 1.1 | 54.4% | 53.3% |
| BenchCAD (with Python tool) | 96.2% | 95.9% |
| DeepSWE 1.1 | 74.2% | 74.1% |
Visual Benchmark Comparison
Verdict
Claude Opus 5.5 leads in 2 out of 4 comparison categories.
Both models show comparable average scores: Claude Opus 5.5 — 0.7, GPT-6 Astra — 0.7.
Claude Opus 5.5 is 2.5x cheaper: input $4.00/1M vs $10.00/1M tokens.
GPT-6 Astra supports a larger context: 1M vs 1M tokens.
Claude Opus 5.5 is newer: released 9/22/2026 vs 9/4/2026.
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Frequently Asked Questions
Which is better for coding — Claude Opus 5.5 or GPT-6 Astra?
Which model is cheaper — Claude Opus 5.5 or GPT-6 Astra?
Which has a larger context window — Claude Opus 5.5 or GPT-6 Astra?
The Claude Opus 5.5 and GPT-6 Astra comparison is updated for 2026. Data includes benchmark results, API pricing, context window size and other specifications. For more detailed information, visit the Claude Opus 5.5 or GPT-6 Astra page. See also the complete list of AI model comparisons.