> Claude Fable 5.1 is a closed AI model from Anthropic, released 1 Sep 2026. Index score 192 (GPT-4 = 100), rank 4 of 229 ranked models. API price $10 in / $50 out per million tokens, 1M context.

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# Claude Fable 5.1

Anthropic

Released 1 Sep 2026

Closed

Flagship

[Compare](https://themodelindex.org/compare/claude-fable-5-1-vs-kimi-k3/) [Announcement](https://www.anthropic.com/claude-fable-and-mythos-5-1)

192181–203

Index score

#4 of 229 models

4/ 8

Core tests taken

4 of 6 areas · plus 16 anchor tests

Frontier

Versus the frontier at release

set or matched the record

$10/ $50

Price per million tokens

input / output, list price

1M

Context window

tokens it reads at once

## Where it sits · on the frontier

_Chart: Model Index score of every scored model since late 2022, with the best closed and best open model over time_

Among the first models to reach this score.

## Test results · by area · tick = best by any model

Show 13 anchor tests

Reasoning & knowledge

evidence

GPQA Diamond

no result

Humanity's Last Exam

47%

Maths

evidence

FrontierMath T1-3

90%

Coding

evidence

SWE-bench Verified

no result

Terminal-Bench

no result

Agents

evidence

APEX-Agents

69%

Novel problems

evidence

ARC-AGI-2

90%

Long tasks

no evidence yet

METR time horizon

no result

Independent results from the Epoch AI benchmarking hub, best reasoning setting. The core tests are shown here; anchor tests also inform the score and can be shown above.

## What others say · rank on each leaderboard

The Model Index

independent tests, our method

#4

of 219 · 192

LMArena · Maths

maths questions in chat

#4

of 373 · 1517

Artificial Analysis Intelligence Index

overall capability across ten evaluations

#3

of 207 · 53

LMArena · Text

overall chat quality, judged by people

#6

of 388 · 1501

Epoch Capabilities Index

overall capability from many benchmarks

#4

of 239 · 164.8

LiveBench · Overall

overall, with fresh questions to limit contamination

#1

of 58 · 83.4

LMArena · Creative writing

creative writing

#10

of 386 · 1482

LMArena · WebDev

building web apps and front ends

#4

of 123 · 1751

LMArena · Coding

coding questions in chat

#17

of 383 · 1532

LMArena · Documents

working with long documents

#2

of 41 · 1513

LMArena · Vision

understanding images

#14

of 149 · 1287

Further left is better. Leaderboards measure different things: LMArena is people voting blind between two answers, the others are test scores. Click any row for the source.

## Best at · top three among current models

1st

working with long documents

LMArena · Documents

2nd

maths questions in chat

LMArena · Maths

2nd

agentic coding questions

LiveBench · Agentic Coding

2nd

mathematics questions

LiveBench · Mathematics

2nd

language questions

LiveBench · Language

2nd

Humanity's Last Exam

Epoch AI · independent

3rd

understanding images

LMArena · Vision

3rd

coding questions

LiveBench · Coding

3rd

data analysis questions

LiveBench · Data Analysis

3rd

APEX-Agents

Epoch AI · independent

Where this model places in the top three of today's models, on category leaderboards and on our core tests.

## Where to use it · prices checked 1 Oct 2026

#### From the lab

Claude

app · subscription

↗

Claude API

API

↗

#### API providers · 4 · per million tokens, in / out

A

Azure

$10 / $50

cheapest

A

Anthropic

$10 / $50

↗

A

Amazon Bedrock

$10 / $50

↗

G

Google

$10 / $50

↗

Provider prices come from OpenRouter's live listing; going direct to a provider can differ. Subscriptions are the lab's own apps.

## Facts and sources

Released

1 Sep 2026

Announcement

[anthropic.com ↗](https://www.anthropic.com/claude-fable-and-mythos-5-1)

Release entry

Claude Fable 5.1 + Mythos 5.1

Scored as

Claude Fable 5.1

Artificial Analysis index

53 · max with fallback

Output speed

68 tokens/s

Hugging Face

closed weights

## Anthropic releases · around this one

Claude Sonnet 5

Closed

30 JUN 2026

index 169

Claude Opus 5

Closed

24 JUL 2026

index 187

Claude Fable 5.1

Closed

1 SEP 2026

index 192

Claude Mythos 5.1

Closed

1 SEP 2026

Claude Opus 5.5

Closed

22 SEP 2026

index 200

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Source: https://themodelindex.org/models/claude-fable-5-1/ · The Model Index · data as of 2026-10-01