> Claude Fable 5.1 vs Gemini 3.8 Flash: index scores 192 and 171 (GPT-4 = 100), API prices, context windows and results on the same independent tests, side by side.

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# Compare

Side by side on the same independent tests, with price and context. The link in your address bar shares this exact comparison.

[Claude Fable 5.1](https://themodelindex.org/models/claude-fable-5-1/)

[Gemini 3.8 Flash](https://themodelindex.org/models/gemini-3-8-flash/)

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Next to Claude Fable 5.1

Cheapest at this level

Claude Sonnet 5.5

Best open model, measured

Kimi K3

Closest rival, another lab

Gemini 4 Argon

Stronger for the same price

Claude Opus 5.5

The version it replaced

Claude Fable 5

Presets

Best open vs best closed (measured)

Today vs GPT-4 (2023)

Top three labs

US vs China, best of each

[Claude Fable 5.1](https://themodelindex.org/models/claude-fable-5-1/)

192

181–203

Weights

Closed

Released

Sep 2026

Price in / out

$10 / $50

Context

1M

Core tests taken

4 of 8

[Gemini 3.8 Flash](https://themodelindex.org/models/gemini-3-8-flash/)

171

159–182

Weights

Closed

Released

Sep 2026

Price in / out

$0.75 / $3.75

Context

1.05M

Core tests taken

4 of 8

Claude Fable 5.1 leads Gemini 3.8 Flash by 22 points, ahead on 3 of 3 shared core tests, at 13× the price.

## Test by test · independent results · Epoch AI

Claude Fable 5.1

Gemini 3.8 Flash

_Chart: Test results for the selected models_

Only tests that at least two of these models have taken. Bold rows are the core tests shown on every profile; all of these results inform the index score. Task length (METR) is listed below the chart because it is a duration, not a percentage.

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Source: https://themodelindex.org/compare/claude-fable-5-1-vs-gemini-3-8-flash/ · The Model Index · data as of 2026-10-01