# Claude Fable 5.1 vs Claude Sonnet 5.5

Claude Sonnet 5.5 is the cheaper of the 2: for the same tokens, 3 read for each 1 written, Claude Fable 5.1 costs 5 times as much. Below are both price lists, what 8 everyday jobs cost a month on each, and how many tokens the same text takes on each, which can change the answer.

- Page, with a calculator for your own job: https://tecyfy.com/prices/compare/claude-fable-5-1-vs-claude-sonnet-5-5
- Makers: Claude Fable 5.1 from Anthropic, Claude Sonnet 5.5 from Anthropic

## Price per million tokens, in US dollars

| | Claude Fable 5.1 | Claude Sonnet 5.5 |
| --- | --: | --: |
| Input | $10 | $2 |
| Cached input | $0.25 | $0.10 |
| Cache write | $12.50 | $2.50 |
| Output | $50 | $10 |
| Blend, 3 read for each 1 written | $20 | $4 |
| Batch input | $5 | $1 |
| Batch output | $25 | $5 |
| Context window, tokens | 1M | 1M |
| Capability score (Epoch Capabilities Index; GPT-5 is 150) | 165 | 164 |
| Longest answer, tokens | 128K | 128K |

Price change, Claude Sonnet 5.5: Cached input went from $0.20 to $0.10 per million tokens. The price of a cache write did not change.

## 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 Sonnet 5.5 |
| --- | --- | --: | --: |
| A chat question | 300, 500, 100 | $84.00 | $16.80 |
| A hard question, with thinking | 300, 1,400, 100 | $219 | $43.80 |
| A long report, summarised | 60,000, 2,000, 20 | $420 | $84.00 |
| A 40-turn agent task | 2,800,000, 40,000, 10 | $1,629 | $364 |
| A support bot's reply | 4,000, 300, 2,000 | $2,130 | $432 |
| Sort a message into a category | 250, 5, 50,000 | $4,125 | $825 |
| Read an invoice into fields | 1,500, 250, 1,000 | $825 | $165 |
| Review a pull request | 25,000, 4,500, 50 | $713 | $143 |

## Questions

### Which is cheaper, Claude Fable 5.1 or Claude Sonnet 5.5?

Claude Sonnet 5.5 is cheaper: $2 per million tokens read and $10 per million written, against $10 and $50 on Claude Fable 5.1. On a mix of 3 tokens read for each 1 written, Claude Fable 5.1 costs 5 times as much.

### Which is better, Claude Fable 5.1 or Claude Sonnet 5.5?

They cannot be told apart on the Epoch Capabilities Index, an independent score from Epoch AI that combines over 50 benchmarks: Claude Fable 5.1 scores 165 and Claude Sonnet 5.5 164, within the range of doubt around each (GPT-5 is 150). So choose on price and on 10 tasks of your own.

### What does a support bot cost a month on Claude Fable 5.1 and Claude Sonnet 5.5?

At 2,000 replies a day, each reading 4,000 tokens (50 percent of them from cache) and writing 300, it costs $2,130 a month on Claude Fable 5.1 and $432 on Claude Sonnet 5.5: Claude Fable 5.1 costs 4.9 times as much for this job.

### What does an AI agent task cost on Claude Fable 5.1 and Claude Sonnet 5.5?

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 $1.21 on Claude Sonnet 5.5. At 10 tasks a day that is $1,629 and $364 a month.

### Which has the larger context window, Claude Fable 5.1 or Claude Sonnet 5.5?

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 Sonnet 5.5?

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.

### Can I pay less on Claude Fable 5.1 and Claude Sonnet 5.5 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 Sonnet 5.5 $1 and $5.

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