# Claude Fable 5.1 vs Gemini 3.8 Flash

Gemini 3.8 Flash is the cheaper of the 2: for the same tokens, 3 read for each 1 written, Claude Fable 5.1 costs 13 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-gemini-3-8-flash
- Makers: Claude Fable 5.1 from Anthropic, Gemini 3.8 Flash from Google

## Price per million tokens, in US dollars

| | Claude Fable 5.1 | Gemini 3.8 Flash |
| --- | --: | --: |
| Input | $10 | $0.75 |
| Cached input | $0.25 | $0.075 |
| Cache write | $12.50 | not listed |
| Output | $50 | $3.75 |
| Blend, 3 read for each 1 written | $20 | $1.50 |
| Batch input | $5 | not listed |
| Batch output | $25 | not listed |
| Context window, tokens | 1M | 1.05M |
| Capability score (Epoch Capabilities Index; GPT-5 is 150) | 165 | 157 |
| Longest answer, tokens | 128K | 66K |

Gemini 3.8 Flash: Until 31 December 2026. From 1 January 2027 it is $1.50 in, $7.50 out and $0.15 cached.

## The same text, counted by each maker

Our lesson "How AI writes" (https://tecyfy.com/learn/how-ai-works/how-ai-writes), about 1,700 words of English:

- Claude Fable 5.1: about 2,100 to 3,600 tokens. Anthropic does not publish its tokenizer. It says Claude 4.7 and later produce about 30 percent more tokens for the same text than earlier models, and an independent test counted TypeScript at 1.73 times OpenAI's figure. The range runs from OpenAI's count to 1.75 times it.
- Gemini 3.8 Flash: about 2,200 tokens. Google does not publish the Gemini tokenizer. Its rule is that a token is about 4 characters, so the count is the characters divided by 4.

## 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 | Gemini 3.8 Flash |
| --- | --- | --: | --: |
| A chat question | 300, 500, 100 | $84.00 | $6.30 |
| A hard question, with thinking | 300, 1,400, 100 | $219 | $16.43 |
| A long report, summarised | 60,000, 2,000, 20 | $420 | $31.50 |
| A 40-turn agent task | 2,800,000, 40,000, 10 | $1,629 | $165 |
| A support bot's reply | 4,000, 300, 2,000 | $2,130 | $166 |
| Sort a message into a category | 250, 5, 50,000 | $4,125 | $309 |
| Read an invoice into fields | 1,500, 250, 1,000 | $825 | $61.88 |
| Review a pull request | 25,000, 4,500, 50 | $713 | $53.44 |

## Questions

### Which is cheaper, Claude Fable 5.1 or Gemini 3.8 Flash?

Gemini 3.8 Flash is cheaper: $0.75 per million tokens read and $3.75 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 13 times as much.

### Which is better, Claude Fable 5.1 or Gemini 3.8 Flash?

On the Epoch Capabilities Index, an independent score from Epoch AI that combines over 50 benchmarks, Claude Fable 5.1 scores 165 and Gemini 3.8 Flash 157, above the top of the range of doubt around Gemini 3.8 Flash's score (GPT-5 is 150). One score is an average; test both on your own work before you switch.

### What does a support bot cost a month on Claude Fable 5.1 and Gemini 3.8 Flash?

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 $166 on Gemini 3.8 Flash: Claude Fable 5.1 costs 13 times as much for this job.

### What does an AI agent task cost on Claude Fable 5.1 and Gemini 3.8 Flash?

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 55 cents on Gemini 3.8 Flash. At 10 tasks a day that is $1,629 and $165 a month.

### Which has the larger context window, Claude Fable 5.1 or Gemini 3.8 Flash?

Gemini 3.8 Flash, with 1.05M tokens against 1M on Claude Fable 5.1. The window holds your instructions, the files you attach, the conversation so far and the answer, all at once.

### Does the same text take the same number of tokens on Claude Fable 5.1 and Gemini 3.8 Flash?

No. Our lesson "How AI writes", 1,700 words long, is about 2,100 to 3,600 tokens on Claude Fable 5.1 and about 2,200 on Gemini 3.8 Flash. Each maker cuts text its own way, and every extra token is paid for at the model's price.

### Can I pay less on Claude Fable 5.1 and Gemini 3.8 Flash for work that can wait?

On Claude Fable 5.1 only: with a batch, where you collect the answers later, it costs $5 per million tokens read and $25 written. Google's price page lists no batch price for Gemini 3.8 Flash.

## Sources

- [Anthropic: API prices](https://platform.claude.com/docs/en/about-claude/pricing)
- [Google: API prices](https://ai.google.dev/gemini-api/docs/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 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)
- [Claude Fable 5.1 vs Claude Opus 4.8](https://tecyfy.com/prices/compare/claude-fable-5-1-vs-claude-opus-4-8.md)
- [Claude Fable 5.1 vs Claude Opus 4.7](https://tecyfy.com/prices/compare/claude-fable-5-1-vs-claude-opus-4-7.md)