Pyyan / Compare / Claude Opus 5.5 vs GPT-6 Astra
Claude Opus 5.5 vs GPT-6 Astra
2 of 5Language Models · verified 24 Sept 2026
Claude Opus 5.5Anthropiccurrent
GPT-6 AstraOpenAIcurrent| Specification | Claude Opus 5.5 | GPT-6 Astra |
|---|---|---|
| Summary | Fable 5.1's level of work on most tasks, at 40% less to run than Opus 5. | Saturates three of the benchmarks it reports, and ships disabled for enterprise. |
| Context | 1M | 1.05M |
| Input ($/Mtok) | $4 | $10 |
| Output ($/Mtok) | $20 | $50 |
| Licence | Proprietary | Proprietary |
| Max output | 128K | 128K |
| Parameters | Not published | Not published |
| Released | 22 Sep 2026 | 3 Sep 2026 |
| Model ID | claude-opus-5-5 | gpt-6-astra |
| Category | Language Models | Language Models |
| Official | Anthropic ↗ | — |
Highlighted rows are where these differ.
Claude Opus 5.5
- 66.4% on Terminal-Bench 4.0 against 52.3% for Opus 5, on Anthropic's own harness
- Cache reads cut 60% to $0.20, and output more than 30% faster than Opus 5
- Attempts to work around its boundaries 85% less often than Opus 5, Anthropic reports
Best for agentic coding at flagship quality.
GPT-6 Astra
- 97.6% on FrontierMath Tier 4, 99.9% on ARC-AGI-3 and 100% on ExploitBench
- Above 272K input tokens the whole request reprices: input and cache at 2x, output at 1.5x
- Rolls out to OpenAI's Daybreak cyber programme first, and arrives switched off for enterprise
Best for hard reasoning and computer use.