High-volume, cost-sensitive work
Either one
Both cost $20.00 per million tokens on a typical mix of three input tokens for every output token.
Claude Mythos 5.1 vs GPT-6 Astra Pro: price, context and capabilities
Choose Claude Mythos 5.1 for reused prompts and documents (RAG, agents); on the other points the two are level or the data is missing.
In short
- Both cost the same at the headline price ($20.00 / 1M tokens).
- GPT-6 Astra Pro reads more per request: 1.05M tokens against 1M.
- Only Claude Mythos 5.1 offers batch api.
Which should you choose?
Each answer below comes straight from the published prices, specifications and independent benchmark results.
Reused prompts and documents (RAG, agents)
Choose Claude Mythos 5.1
Claude Mythos 5.1 charges $0.25 per million cached input tokens, against $1.00 for GPT-6 Astra Pro.
Monthly cost at three volumes
| Volume | Claude Mythos 5.1 | GPT-6 Astra Pro | Difference |
|---|---|---|---|
| Prototype: 1M input, 250K output tokens | $22.50 | $22.50 | = |
| Production: 20M input, 5M output tokens | $450.00 | $450.00 | = |
| Scale: 500M input, 100M output tokens | $10,000 | $10,000 | = |
Standard rates, without caching or batch discounts. Volumes are per month.
Specifications side by side
| Claude Mythos 5.1 | GPT-6 Astra Pro | |
|---|---|---|
| Provider | Anthropic | OpenAI |
| Category | Language models | Language models |
| Status | Generally available · Limited access | Generally available |
| Headline price | $20.00 / 1M tokens | $20.00 / 1M tokens |
| Input | $10.00 / 1M tokens | $10.00 / 1M tokens |
| Output | $50.00 / 1M tokens | $50.00 / 1M tokens |
| Cached input | $0.25 / 1M tokens | $1.00 / 1M tokens |
| Context window | 1M | 1.05M |
| Max output | 128k | 128k |
| Released | September 2026 | Sep 4, 2026 |
| Knowledge cutoff | No data | 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-mythos-5-1 | gpt-6-astra-pro |
Frequently asked questions
Should I choose Claude Mythos 5.1 or GPT-6 Astra Pro?
Choose Claude Mythos 5.1 for reused prompts and documents (RAG, agents); on the other points the two are level or the data is missing.
Which is cheaper, Claude Mythos 5.1 or GPT-6 Astra Pro?
Both cost the same at the headline price ($20.00 / 1M tokens).
Which has the larger context window, Claude Mythos 5.1 or GPT-6 Astra Pro?
GPT-6 Astra Pro reads more per request: 1.05M tokens against 1M.
What is the difference between Claude Mythos 5.1 and GPT-6 Astra Pro?
Claude Mythos 5.1 is made by Anthropic and GPT-6 Astra Pro by OpenAI. Both cost the same at the headline price ($20.00 / 1M tokens). GPT-6 Astra Pro reads more per request: 1.05M tokens against 1M. Only Claude Mythos 5.1 offers batch api.
How much do Claude Mythos 5.1 and GPT-6 Astra Pro cost per month?
At 20 million input and 5 million output tokens a month, Claude Mythos 5.1 costs $450.00 and GPT-6 Astra Pro costs $450.00, at standard rates.