Claude Opus 5.5 vs GPT-6 Astra
A side-by-side look at Claude Opus 5.5 from Anthropic and GPT-6 Astra from OpenAI: list prices, context windows, licensing and capabilities, with monthly costs worked out for three common workloads.
The short version
- Lower list price: Claude Opus 5.5, about 2.5× cheaper on a blended basis (three parts input to one part output).
- Larger context window: GPT-6 Astra (1.05M vs 1M tokens).
- Inputs: Claude Opus 5.5 accepts text, images, pdf; GPT-6 Astra accepts text, images.
- Newer release: Claude Opus 5.5 (September 22, 2026).
Specs side by side
| Claude Opus 5.5 | GPT-6 Astra | |
|---|---|---|
| Provider | Anthropic | OpenAI |
| Released | Sep 22, 2026 | Sep 3, 2026 |
| Status | Current | Current |
| Weights and license | Closed Proprietary | Closed Proprietary |
| Tier | Frontier | Frontier |
| Context window | 1M | 1.05M |
| Max output | 125K | 125K |
| Input per 1M tokens | $4 | $10 |
| Output per 1M tokens | $20 | $50 |
| Cached input per 1M | $0.20 | $1 |
| Input types | Text, Images, PDF | Text, Images |
| Reasoning mode | Yes | Yes |
| Tool calling | Yes | Yes |
| Parameters | Undisclosed | Undisclosed |
Highlighted cells are better on that line: lower price or larger limit. List prices, standard tier, checked October 10, 2026.
What they cost for real workloads
| Workload (monthly) | Claude Opus 5.5 | GPT-6 Astra | Difference |
|---|---|---|---|
| Support chatbot30,000 conversations a month, 2,000 input and 400 output tokens each | $480 | $1,200 | Claude Opus 5.5 saves $720 |
| Document summaries2,000 documents a month, 12,000 input and 800 output tokens each | $128 | $320 | Claude Opus 5.5 saves $192 |
| Coding agent1,000 tasks a month, 60,000 input and 6,000 output tokens each | $360 | $900 | Claude Opus 5.5 saves $540 |
Standard rates without caching or batch discounts. Try your own volumes.
Choose Claude Opus 5.5 if
- you mainly need it for enterprise, which Anthropic emphasizes for this model
- cost per token is a deciding factor
- your inputs include pdf
- anthropic's recommended default for most workloads
- 1M-token context with no long-context surcharge
Choose GPT-6 Astra if
- you mainly need it for research, which OpenAI emphasizes for this model
- you need more than 1M tokens of context in one request
- 1.05M-token context window and 128K-token output limit
- reasoning effort from low to max
Our take
Both are positioned for agents, coding, long documents. On list price the gap is about 2.5×, which matters most for high-volume, input-heavy workloads. Quality differences shift with every release, so treat this page as a shortlist tool: run 20-50 of your real tasks through both, score the outputs, and divide the bill by the number of tasks each one got right.
Read the full profiles: Claude Opus 5.5 and GPT-6 Astra. For help designing that test, see how to read LLM benchmarks.
Frequently asked questions
Which is cheaper, Claude Opus 5.5 or GPT-6 Astra?
Claude Opus 5.5 has the lower list price: $4 input and $20 output per million tokens, versus $10 and $50. Discounts for caching and batch processing can change the real bill, so price your own token mix.
Which has the bigger context window?
GPT-6 Astra accepts 1.05M tokens, compared with 1M for Claude Opus 5.5.
Can I run Claude Opus 5.5 or GPT-6 Astra on my own hardware?
Claude Opus 5.5 is closed, so only through hosted APIs. GPT-6 Astra is closed, so only through hosted APIs.
Is Claude Opus 5.5 better than GPT-6 Astra?
It depends on the task. Public benchmarks and arena rankings move with every release and rarely match a specific workload. Use the specs here to shortlist, then test both on your own prompts and compare accuracy, latency and cost per correct answer.
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