# Claude Mythos 5.1 API pricing

Claude Mythos 5.1 is an earlier Anthropic model, still sold. It costs $10 per million tokens it reads and $50 per million it writes, $20 on a mix of 3 read for each 1 written. Anthropic's newest models are Claude Fable 5.1, Claude Opus 5.5, Claude Sonnet 5.5 and Claude Haiku 5.5. Below are every price Anthropic lists for it, and what 8 everyday jobs cost a month on it.

- Page: https://tecyfy.com/prices/claude-mythos-5-1
- Maker: Anthropic

## Price per million tokens, in US dollars

| | Price |
| --- | --: |
| Input | $10 |
| Cached input | $0.25 |
| Cache write | $12.50 |
| Output | $50 |
| Blend, 3 read for each 1 written | $20 |
| Batch input | $5 |
| Batch output | $25 |
| Context window, tokens | 1M |
| Longest answer, tokens | 128K |
| Capability score (Epoch Capabilities Index; GPT-5 is 150) | not scored |

Limited availability.

## What 8 everyday jobs cost a month

Each job at its usual runs a day, for 30 days, at the standard price.

| Job | Tokens in, out, runs a day | A run | A month |
| --- | --- | --: | --: |
| A chat question | 300, 500, 100 | 2.8 cents | $84.00 |
| A hard question, with thinking | 300, 1,400, 100 | 7.3 cents | $219 |
| A long report, summarised | 60,000, 2,000, 20 | 70 cents | $420 |
| A 40-turn agent task | 2,800,000, 40,000, 10 | $5.43 | $1,629 |
| A support bot's reply | 4,000, 300, 2,000 | 3.6 cents | $2,130 |
| Sort a message into a category | 250, 5, 50,000 | 0.27 cents | $4,125 |
| Read an invoice into fields | 1,500, 250, 1,000 | 2.8 cents | $825 |
| Review a pull request | 25,000, 4,500, 50 | 48 cents | $713 |

## Questions

### How much does Claude Mythos 5.1 cost?

Claude Mythos 5.1 costs $10 per million input tokens, the text it reads, and $50 per million output tokens, the text it writes, thinking included. On a mix of 3 tokens read for each 1 written, that is $20 per million.

### How much does cached input cost on Claude Mythos 5.1?

Text Claude Mythos 5.1 reads again from the cache costs $0.25 per million tokens, against $10 the first time. Putting text in the cache costs $12.50 per million, so a long prompt sent again and again costs far less after the first time.

### Does Claude Mythos 5.1 have a batch price?

Yes. With a batch, where you send many requests and collect the answers later instead of at once, Claude Mythos 5.1 costs $5 per million tokens read and $25 per million written.

### What is the context window of Claude Mythos 5.1?

Claude Mythos 5.1 holds 1M tokens at once, about 1,500 pages of English text, and writes up to 128K tokens in one answer. The window holds your instructions, the files you attach, the conversation so far and the answer.

### How good is Claude Mythos 5.1?

Epoch AI has no independent score for Claude Mythos 5.1 yet. Run the same 10 tasks of your own on it and on a model you know, and compare the answers and the bills.

### Should I still use Claude Mythos 5.1?

It is still sold, so it keeps working, but Anthropic's newest models are Claude Fable 5.1, Claude Opus 5.5, Claude Sonnet 5.5 and Claude Haiku 5.5. Compare its price with theirs below, and run your own tasks on the newer model before you move.

### What does a support bot cost a month on Claude Mythos 5.1?

At 2,000 replies a day, each reading 4,000 tokens (50 percent of them from cache) and writing 300, a support bot costs 3.6 cents a reply on Claude Mythos 5.1, $2,130 a month.

### What does an AI agent task cost on Claude Mythos 5.1?

One 40-turn task that reads 2,800,000 tokens in all, 90 percent of them from cache, and writes 40,000, costs $5.43 on Claude Mythos 5.1. At 10 tasks a day that is $1,629 a month.

## Sources

- [Anthropic: API prices](https://platform.claude.com/docs/en/about-claude/pricing)
- Every model's prices as [JSON](https://tecyfy.com/prices.json) or [CSV](https://tecyfy.com/prices.csv), free to use

## Compare

- [Claude Fable 5.1 vs Claude Mythos 5.1](https://tecyfy.com/prices/compare/claude-fable-5-1-vs-claude-mythos-5-1.md)
- [Claude Mythos 5.1 vs Claude Opus 5.5](https://tecyfy.com/prices/compare/claude-mythos-5-1-vs-claude-opus-5-5.md)
- [Claude Mythos 5.1 vs Claude Sonnet 5.5](https://tecyfy.com/prices/compare/claude-mythos-5-1-vs-claude-sonnet-5-5.md)
- [Claude Haiku 5.5 vs Claude Mythos 5.1](https://tecyfy.com/prices/compare/claude-haiku-5-5-vs-claude-mythos-5-1.md)

## Anthropic's other models

- [Claude Fable 5.1](https://tecyfy.com/prices/claude-fable-5-1.md)
- [Claude Opus 5.5](https://tecyfy.com/prices/claude-opus-5-5.md)
- [Claude Sonnet 5.5](https://tecyfy.com/prices/claude-sonnet-5-5.md)
- [Claude Haiku 5.5](https://tecyfy.com/prices/claude-haiku-5-5.md)
- [Claude Fable 5](https://tecyfy.com/prices/claude-fable-5.md)
- [Claude Mythos 5](https://tecyfy.com/prices/claude-mythos-5.md)
- [Claude Opus 5](https://tecyfy.com/prices/claude-opus-5.md)
- [Claude Opus 4.8](https://tecyfy.com/prices/claude-opus-4-8.md)
- [Claude Opus 4.7](https://tecyfy.com/prices/claude-opus-4-7.md)
- [Claude Opus 4.6](https://tecyfy.com/prices/claude-opus-4-6.md)
- [Claude Opus 4.5](https://tecyfy.com/prices/claude-opus-4-5.md)
- [Claude Sonnet 5](https://tecyfy.com/prices/claude-sonnet-5.md)
- [Claude Sonnet 4.6](https://tecyfy.com/prices/claude-sonnet-4-6.md)
- [Claude Sonnet 4.5](https://tecyfy.com/prices/claude-sonnet-4-5.md)
- [Claude Haiku 4.5](https://tecyfy.com/prices/claude-haiku-4-5.md)