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: 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 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.
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.
Monthly cost at three volumes
| Volume | Claude Mythos 5.1 | GPT-6 Astra | 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 | |
|---|---|---|
| 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 3, 2026 |
| Knowledge cutoff | No data | 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-mythos-5-1 | gpt-6-astra |
Benchmarks side by side
Leader in bold.
| Benchmark | Claude Mythos 5.1 | GPT-6 Astra |
|---|---|---|
| Intelligence Index | No data | 52.7 |
| SciCode | No data | 56.5% |
| GPQA Diamond | No data | 96.1% |
| Humanity's Last Exam | No data | 54.7% |
| MMMU-Pro (visual reasoning) | No data | 86.9% |
| Long-context reasoning (AA-LCR) | No data | 80.7% |
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 Mythos 5.1 or GPT-6 Astra?
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?
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?
GPT-6 Astra reads more per request: 1.05M tokens against 1M.
What is the difference between Claude Mythos 5.1 and GPT-6 Astra?
Claude Mythos 5.1 is made by Anthropic and GPT-6 Astra by OpenAI. Both cost the same at the headline price ($20.00 / 1M tokens). GPT-6 Astra reads more per request: 1.05M tokens against 1M.
How much do Claude Mythos 5.1 and GPT-6 Astra 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 costs $450.00, at standard rates.