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 Pro: price, context and capabilities
Choose Claude Opus 5.5 for high-volume, cost-sensitive work, writing and code generation and reused prompts and documents (RAG, agents); 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 Pro at the headline price ($8.00 / 1M tokens vs $20.00 / 1M tokens).
- GPT-6 Astra Pro reads more per request: 1.05M tokens against 1M.
- Only Claude Opus 5.5 offers batch api.
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 Pro. 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 Pro.
Monthly cost at three volumes
| Volume | Claude Opus 5.5 | GPT-6 Astra Pro | 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 Pro | |
|---|---|---|
| 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 4, 2026 |
| Knowledge cutoff | June 2026 | No data |
| Licence | Proprietary | Proprietary |
| Capabilities | Vision, Reasoning, Tool calling, Structured output, Prompt caching, Batch API | Vision, Reasoning, Tool calling, Structured output, Prompt caching |
| API model id | claude-opus-5-5 | gpt-6-astra-pro |
Benchmarks side by side
Leader in bold.
| Benchmark | Claude Opus 5.5 | GPT-6 Astra Pro |
|---|---|---|
| Intelligence Index | 57.6 | No data |
| SciCode | 66.9% | No data |
| Humanity's Last Exam | 61.4% | No data |
| MMMU-Pro (visual reasoning) | 87.7% | No data |
| Long-context reasoning (AA-LCR) | 84.7% | No data |
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 Pro?
Choose Claude Opus 5.5 for high-volume, cost-sensitive work, writing and code generation and reused prompts and documents (RAG, agents); on the other points the two are level or the data is missing.
Which is cheaper, Claude Opus 5.5 or GPT-6 Astra Pro?
Claude Opus 5.5 is 60% cheaper than GPT-6 Astra Pro 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 Pro?
GPT-6 Astra Pro reads more per request: 1.05M tokens against 1M.
What is the difference between Claude Opus 5.5 and GPT-6 Astra Pro?
Claude Opus 5.5 is made by Anthropic and GPT-6 Astra Pro by OpenAI. Claude Opus 5.5 is 60% cheaper than GPT-6 Astra Pro at the headline price ($8.00 / 1M tokens vs $20.00 / 1M tokens). GPT-6 Astra Pro reads more per request: 1.05M tokens against 1M. Only Claude Opus 5.5 offers batch api.
How much do Claude Opus 5.5 and GPT-6 Astra Pro 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 Pro costs $450.00, at standard rates.