High-volume, cost-sensitive work
Choose Claude Opus 5.5
Claude Opus 5.5 costs 60% less on a typical mix of three input tokens for every output token ($8.00 against $20.00 per million tokens).
Claude Opus 5.5 vs GPT-6 Astra: price, context and capabilities
Choose Claude Opus 5.5 for high-volume, cost-sensitive work, writing and code generation, reused prompts and documents (RAG, agents), the hardest reasoning tasks, reasoning over long documents and the most recent knowledge; on the other points the two are level or the data is missing.
In short
- Claude Opus 5.5 is 60% cheaper than GPT-6 Astra at the headline price ($8.00 / 1M tokens vs $20.00 / 1M tokens).
- GPT-6 Astra reads more per request: 1.05M tokens against 1M.
Which should you choose?
Each answer below comes straight from the published prices, specifications and independent benchmark results.
Writing and code generation
Choose Claude Opus 5.5
Claude Opus 5.5 charges $20.00 per million output tokens, against $50.00 for GPT-6 Astra. Output dominates the bill when answers are long.
Reused prompts and documents (RAG, agents)
Choose Claude Opus 5.5
Claude Opus 5.5 charges $0.20 per million cached input tokens, against $1.00 for GPT-6 Astra.
Hardest reasoning tasks
Choose Claude Opus 5.5
Claude Opus 5.5 scores 57.6 on the Artificial Analysis Intelligence Index, against 52.7 for GPT-6 Astra.
Reasoning over long documents
Choose Claude Opus 5.5
Claude Opus 5.5 scores 84.7% on Long-context reasoning (AA-LCR), against 80.7% for GPT-6 Astra.
Most recent knowledge
Choose Claude Opus 5.5
Claude Opus 5.5 was trained on data up to June 2026, against April 2026 for GPT-6 Astra.
Monthly cost at three volumes
| Volume | Claude Opus 5.5 | GPT-6 Astra | Difference |
|---|---|---|---|
| Prototype: 1M input, 250K output tokens | $9.00 | $22.50 | Claude Opus 5.5, $13.50 less |
| Production: 20M input, 5M output tokens | $180.00 | $450.00 | Claude Opus 5.5, $270.00 less |
| Scale: 500M input, 100M output tokens | $4,000 | $10,000 | Claude Opus 5.5, $6,000 less |
Standard rates, without caching or batch discounts. Volumes are per month.
Specifications side by side
| Claude Opus 5.5 | GPT-6 Astra | |
|---|---|---|
| Provider | Anthropic | OpenAI |
| Category | Language models | Language models |
| Status | Generally available | Generally available |
| Headline price | $8.00 / 1M tokens | $20.00 / 1M tokens |
| Input | $4.00 / 1M tokens | $10.00 / 1M tokens |
| Output | $20.00 / 1M tokens | $50.00 / 1M tokens |
| Cached input | $0.20 / 1M tokens | $1.00 / 1M tokens |
| Context window | 1M | 1.05M |
| Max output | 128k | 128k |
| Released | September 2026 | Sep 3, 2026 |
| Knowledge cutoff | June 2026 | April 2026 |
| Licence | Proprietary | Proprietary |
| Capabilities | Vision, Reasoning, Tool calling, Structured output, Prompt caching, Batch API | Vision, Reasoning, Tool calling, Structured output, Prompt caching, Batch API |
| API model id | claude-opus-5-5 | gpt-6-astra |
Benchmarks side by side
Leader in bold.
| Benchmark | Claude Opus 5.5 | GPT-6 Astra |
|---|---|---|
| Intelligence Index | 57.6 | 52.7 |
| SciCode | 66.9% | 56.5% |
| Humanity's Last Exam | 61.4% | 54.7% |
| MMMU-Pro (visual reasoning) | 87.7% | 86.9% |
| Long-context reasoning (AA-LCR) | 84.7% | 80.7% |
| GPQA Diamond | No data | 96.1% |
Independent evaluations by Artificial Analysis, run the same way for every model, at the reasoning setting shown. Percentages unless marked as an index.
Frequently asked questions
Should I choose Claude Opus 5.5 or GPT-6 Astra?
Choose Claude Opus 5.5 for high-volume, cost-sensitive work, writing and code generation, reused prompts and documents (RAG, agents), the hardest reasoning tasks, reasoning over long documents and the most recent knowledge; on the other points the two are level or the data is missing.
Which is cheaper, Claude Opus 5.5 or GPT-6 Astra?
Claude Opus 5.5 is 60% cheaper than GPT-6 Astra at the headline price ($8.00 / 1M tokens vs $20.00 / 1M tokens).
Which has the larger context window, Claude Opus 5.5 or GPT-6 Astra?
GPT-6 Astra reads more per request: 1.05M tokens against 1M.
What is the difference between Claude Opus 5.5 and GPT-6 Astra?
Claude Opus 5.5 is made by Anthropic and GPT-6 Astra by OpenAI. Claude Opus 5.5 is 60% cheaper than GPT-6 Astra at the headline price ($8.00 / 1M tokens vs $20.00 / 1M tokens). GPT-6 Astra reads more per request: 1.05M tokens against 1M.
How much do Claude Opus 5.5 and GPT-6 Astra cost per month?
At 20 million input and 5 million output tokens a month, Claude Opus 5.5 costs $180.00 and GPT-6 Astra costs $450.00, at standard rates.