> Claude Mythos Preview is a closed AI model from Anthropic, released 7 Apr 2026.

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# Claude Mythos Preview

Anthropic

Released 7 Apr 2026

Closed

Flagship

Date verified

[Compare](https://themodelindex.org/compare/claude-mythos-preview-vs-kimi-k2-6/) [Announcement](https://www.anthropic.com/research/mythos-preview)

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Index score

Not yet evaluated independently

1/ 8

Core tests taken

1 of 6 areas · plus 0 anchor tests

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Versus the frontier at release

Replaced by [Claude Mythos 5](https://themodelindex.org/models/claude-mythos-5/)

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Price per million tokens

no public API price found

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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

Reasoning & knowledge

no evidence yet

GPQA Diamond

no result

Humanity's Last Exam

no result

Maths

no evidence yet

FrontierMath T1-3

no result

Coding

no evidence yet

SWE-bench Verified

no result

Terminal-Bench

no result

Agents

no evidence yet

APEX-Agents

no result

Novel problems

no evidence yet

ARC-AGI-2

no result

Long tasks

evidence

METR time horizon

17 h

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

Not on any of the rankings we follow yet.

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

METR time horizon

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

↗

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

7 Apr 2026

Announcement

[anthropic.com ↗](https://www.anthropic.com/research/mythos-preview)

Release entry

Claude Mythos Preview (restricted; Project Glasswing)

Scored as

Claude Mythos Preview

Artificial Analysis index

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Output speed

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Hugging Face

closed weights

## Anthropic releases · around this one

Claude Opus 4.6

Closed

5 FEB 2026

index 167

Claude Sonnet 4.6

Closed

17 FEB 2026

index 160

Claude Mythos Preview

Closed

7 APR 2026

Claude Opus 4.7

Closed

16 APR 2026

index 169

Claude Opus 4.8

Closed

28 MAY 2026

index 174

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