High-volume, cost-sensitive work
Choose Chat Latest
Chat Latest costs 44% less on a typical mix of three input tokens for every output token ($11.25 against $20.00 per million tokens).
Chat Latest vs Claude Mythos 5.1: price, context and capabilities
Choose Chat Latest for high-volume, cost-sensitive work and writing and code generation. Choose Claude Mythos 5.1 for reused prompts and documents (RAG, agents), very long inputs and the latest release.
In short
- Chat Latest is 44% cheaper than Claude Mythos 5.1 at the headline price ($11.25 / 1M tokens vs $20.00 / 1M tokens).
- Claude Mythos 5.1 reads more per request: 1M tokens against 400k.
- Claude Mythos 5.1 is the newer model (September 2026, against May 5, 2026).
- Only Claude Mythos 5.1 offers reasoning.
Which should you choose?
Each answer below comes straight from the published prices, specifications and independent benchmark results.
Writing and code generation
Choose Chat Latest
Chat Latest charges $30.00 per million output tokens, against $50.00 for Claude Mythos 5.1. Output dominates the bill when answers are long.
Reused prompts and documents (RAG, agents)
Choose Claude Mythos 5.1
Claude Mythos 5.1 charges $0.25 per million cached input tokens, against $0.50 for Chat Latest.
Very long inputs
Choose Claude Mythos 5.1
Claude Mythos 5.1 reads up to 1M tokens per request, against 400k for Chat Latest.
Latest release
Choose Claude Mythos 5.1
Claude Mythos 5.1 is the newer release (September 2026, against May 5, 2026 for Chat Latest).
Monthly cost at three volumes
| Volume | Chat Latest | Claude Mythos 5.1 | Difference |
|---|---|---|---|
| Prototype: 1M input, 250K output tokens | $12.50 | $22.50 | Chat Latest, $10.00 less |
| Production: 20M input, 5M output tokens | $250.00 | $450.00 | Chat Latest, $200.00 less |
| Scale: 500M input, 100M output tokens | $5,500 | $10,000 | Chat Latest, $4,500 less |
Standard rates, without caching or batch discounts. Volumes are per month.
Specifications side by side
| Chat Latest | Claude Mythos 5.1 | |
|---|---|---|
| Provider | OpenAI | Anthropic |
| Category | Language models | Language models |
| Status | Generally available | Generally available · Limited access |
| Headline price | $11.25 / 1M tokens | $20.00 / 1M tokens |
| Input | $5.00 / 1M tokens | $10.00 / 1M tokens |
| Output | $30.00 / 1M tokens | $50.00 / 1M tokens |
| Cached input | $0.50 / 1M tokens | $0.25 / 1M tokens |
| Context window | 400k | 1M |
| Max output | 128k | 128k |
| Released | May 5, 2026 | September 2026 |
| Knowledge cutoff | April 2026 | No data |
| Licence | Proprietary | Proprietary |
| Capabilities | Vision, Tool calling, Structured output, Prompt caching, Batch API | Vision, Reasoning, Tool calling, Structured output, Prompt caching, Batch API |
| API model id | chat-latest | claude-mythos-5-1 |
Frequently asked questions
Should I choose Chat Latest or Claude Mythos 5.1?
Choose Chat Latest for high-volume, cost-sensitive work and writing and code generation. Choose Claude Mythos 5.1 for reused prompts and documents (RAG, agents), very long inputs and the latest release.
Which is cheaper, Chat Latest or Claude Mythos 5.1?
Chat Latest is 44% cheaper than Claude Mythos 5.1 at the headline price ($11.25 / 1M tokens vs $20.00 / 1M tokens).
Which has the larger context window, Chat Latest or Claude Mythos 5.1?
Claude Mythos 5.1 reads more per request: 1M tokens against 400k.
What is the difference between Chat Latest and Claude Mythos 5.1?
Chat Latest is made by OpenAI and Claude Mythos 5.1 by Anthropic. Chat Latest is 44% cheaper than Claude Mythos 5.1 at the headline price ($11.25 / 1M tokens vs $20.00 / 1M tokens). Claude Mythos 5.1 reads more per request: 1M tokens against 400k. Claude Mythos 5.1 is the newer model (September 2026, against May 5, 2026). Only Claude Mythos 5.1 offers reasoning.
How much do Chat Latest and Claude Mythos 5.1 cost per month?
At 20 million input and 5 million output tokens a month, Chat Latest costs $250.00 and Claude Mythos 5.1 costs $450.00, at standard rates.
Which is newer, Chat Latest or Claude Mythos 5.1?
Claude Mythos 5.1 was released on September 2026 and Chat Latest on May 5, 2026.