Model comparison
Claude Opus 5.5 vs GPT-6 Astra
Claude Opus 5.5 is the cheaper of the two on input tokens, by a factor of 2.5. Claude Opus 5.5 lists $4 in and $20 out per million tokens with a 1M context window; GPT-6 Astra lists $10 and $50 with 1.05M.
| Claude Opus 5.5 | GPT-6 Astra | |
|---|---|---|
| Developer | Anthropic | OpenAI |
| Input / 1M tokens | $4 | $10 |
| Output / 1M tokens | $20 | $50 |
| Context window | 1M | 1.05M |
| Max output | 128K | 128K |
| Modality | Multimodal | Multimodal |
| Open weights | No | No |
| Released | 2026-09-22 | 2026-09-03 |
| Source | Provider documentation | Provider documentation |
| Illustrative month* | $240 | $600 |
* 100 calls a day, about 10,000 tokens in and 2,000 out each, at list price, before caching, batching or volume discounts. Illustrative only. Pricing and context data verified 2026-10-11; "Secondary" figures come from pricing aggregators and trade press, so check the provider before relying on them. No benchmark scores: see methodology.
Claude Opus 5.5
Anthropic's current default recommendation for most workloads: long-running agentic coding and knowledge work at $4 / $20, a fifth cheaper than Opus 5. Thinking is always on and depth is set with the effort parameter.
- Watch: Thinking cannot be disabled; thinking type disabled or enabled returns a 400 error
- Watch: tool_choice any and tool return a 400 error
GPT-6 Astra
OpenAI's flagship and most capable model, built to carry hard reasoning, coding, computer use and research from a request to a finished result. The most expensive model on OpenAI's general price card.
- Watch: No none reasoning effort, custom temperature, top_p or logprobs
- Watch: Tool calling requires the Responses API
Other comparisons