# Claude Fable 5.1 vs Claude Mythos 5.1

Claude Fable 5.1 is one of Anthropic's newest models and Claude Mythos 5.1 an earlier one, so this is also what moving up costs or saves. Claude Fable 5.1 and Claude Mythos 5.1 charge the same per token: $10 per million tokens read and $50 per million written. The bill can still differ, because the same text can be a different number of tokens on each. Below are both price lists, 8 everyday jobs priced on each, and the count for one text.

- Page, with a calculator for your own job: https://tecyfy.com/prices/compare/claude-fable-5-1-vs-claude-mythos-5-1
- Makers: Claude Fable 5.1 from Anthropic, Claude Mythos 5.1 from Anthropic

## Price per million tokens, in US dollars

| | Claude Fable 5.1 | Claude Mythos 5.1 |
| --- | --: | --: |
| Input | $10 | $10 |
| Cached input | $0.25 | $0.25 |
| Cache write | $12.50 | $12.50 |
| Output | $50 | $50 |
| Blend, 3 read for each 1 written | $20 | $20 |
| Batch input | $5 | $5 |
| Batch output | $25 | $25 |
| Context window, tokens | 1M | 1M |
| Capability score (Epoch Capabilities Index; GPT-5 is 150) | 165 | not listed |
| Longest answer, tokens | 128K | 128K |

Claude Mythos 5.1: Limited availability.

## What 8 everyday jobs cost a month on each

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

| Job | Tokens in, out, runs a day | Claude Fable 5.1 | Claude Mythos 5.1 |
| --- | --- | --: | --: |
| A chat question | 300, 500, 100 | $84.00 | $84.00 |
| A hard question, with thinking | 300, 1,400, 100 | $219 | $219 |
| A long report, summarised | 60,000, 2,000, 20 | $420 | $420 |
| A 40-turn agent task | 2,800,000, 40,000, 10 | $1,629 | $1,629 |
| A support bot's reply | 4,000, 300, 2,000 | $2,130 | $2,130 |
| Sort a message into a category | 250, 5, 50,000 | $4,125 | $4,125 |
| Read an invoice into fields | 1,500, 250, 1,000 | $825 | $825 |
| Review a pull request | 25,000, 4,500, 50 | $713 | $713 |

## Questions

### Which is cheaper, Claude Fable 5.1 or Claude Mythos 5.1?

Per token, neither: both charge $10 per million tokens read and $50 per million written. The same text can still be a different number of tokens on each, so the bills can differ.

### Which is better, Claude Fable 5.1 or Claude Mythos 5.1?

Claude Fable 5.1 scores 165 on the Epoch Capabilities Index, an independent score from Epoch AI that combines over 50 benchmarks (GPT-5 is 150). Claude Mythos 5.1 has no independent score yet, so the only fair test is to run the same 10 tasks on both.

### What does an AI agent task cost on Claude Fable 5.1 and 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 Fable 5.1 and $5.43 on Claude Mythos 5.1. At 10 tasks a day that is $1,629 and $1,629 a month.

### Which has the larger context window, Claude Fable 5.1 or Claude Mythos 5.1?

Neither: both hold 1M tokens at once, about 1,500 pages of English text.

### Does the same text take the same number of tokens on Claude Fable 5.1 and Claude Mythos 5.1?

Yes, both are counted the same way: our lesson "How AI writes", 1,700 words long, is about 2,100 to 3,600 tokens on each.

### Is it cheaper to move from Claude Mythos 5.1 to Claude Fable 5.1?

Per token it costs the same: $10 per million tokens read and $50 written on both. The newer model may still use a different number of tokens for the same work.

### Can I pay less on Claude Fable 5.1 and Claude Mythos 5.1 for work that can wait?

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

## Sources

- [Anthropic: API prices](https://platform.claude.com/docs/en/about-claude/pricing)
- [Epoch Capabilities Index, by Epoch AI (CC BY 4.0)](https://epoch.ai/benchmarks/eci)

## Other comparisons

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