Model Comparison

Claude Opus 4.5 vs Claude Mythos PreviewWhich is better in 2026?

Claude Mythos Preview significantly outperforms across most benchmarks. Claude Opus 4.5 is 5.0x cheaper per token.

Verdict: Claude Opus 4.5 vs Claude Mythos Preview — which is better?

Claude Opus 4.5 (by Anthropic) and Claude Mythos Preview (by Anthropic) are two of the AI models people compare most. Here is how they stack up on benchmarks, price and capabilities, and which one to pick in 2026.

Claude Opus 4.5 outperforms in 0 benchmarks, while Claude Mythos Preview is better at 4 benchmarks (GPQA, MMMLU, SWE-Bench Verified, Terminal-Bench 2.0). Claude Mythos Preview significantly outperforms across most benchmarks.

On price, Claude Opus 4.5 is roughly 5.0x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.

Choose Claude Opus 4.5 if…

  • cost matters — it's about 5.0x cheaper per token

Choose Claude Mythos Preview if…

  • you want the strongest raw capability — it leads on 4 of 4 shared benchmarks
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Performance Benchmarks

Comparative analysis across standard metrics

4 benchmarks

Claude Opus 4.5 outperforms in 0 benchmarks, while Claude Mythos Preview is better at 4 benchmarks (GPQA, MMMLU, SWE-Bench Verified, Terminal-Bench 2.0).

Claude Mythos Preview significantly outperforms across most benchmarks.

Sun Jun 07 2026 • llm-stats.com

Arena Performance

Human preference votes

Pricing Analysis

Price comparison per million tokens

Claude Opus 4.5 costs less

For input processing, Claude Opus 4.5 ($5.00/1M tokens) is 5.0x cheaper than Claude Mythos Preview ($25.00/1M tokens).

For output processing, Claude Opus 4.5 ($25.00/1M tokens) is 5.0x cheaper than Claude Mythos Preview ($125.00/1M tokens).

In conclusion, Claude Mythos Preview is more expensive than Claude Opus 4.5.*

* Using a 3:1 ratio of input to output tokens

Lowest available price from all providers
Sun Jun 07 2026 • llm-stats.com
Anthropic
Claude Opus 4.5
Input tokens$5.00
Output tokens$25.00
Best providerAnthropic
Anthropic
Claude Mythos Preview
Input tokens$25.00
Output tokens$125.00
Best providerAnthropic
Notice missing or incorrect data?Start an Issue→

Context Window

Maximum input and output token capacity

Only Claude Opus 4.5 specifies input context (200,000 tokens). Only Claude Opus 4.5 specifies output context (64,000 tokens).

Anthropic
Claude Opus 4.5
Input200,000 tokens
Output64,000 tokens
Anthropic
Claude Mythos Preview
Input- tokens
Output- tokens
Sun Jun 07 2026 • llm-stats.com

Input Capabilities

Supported data types and modalities

Both Claude Opus 4.5 and Claude Mythos Preview support multimodal inputs.

They are both capable of processing various types of data, offering versatility in application.

Claude Opus 4.5

Text
Images
Audio
Video

Claude Mythos Preview

Text
Images
Audio
Video

License

Usage and distribution terms

Both models are licensed under proprietary licenses.

Both models have usage restrictions defined by their respective organizations.

Claude Opus 4.5

Proprietary

Closed source

Claude Mythos Preview

Proprietary

Closed source

Release Timeline

When each model was launched

Claude Opus 4.5 was released on 2025-11-24, while Claude Mythos Preview's release date is not specified.

We can confirm Claude Opus 4.5's release timeline, but cannot make a direct age comparison without Claude Mythos Preview's release date.

Claude Opus 4.5

Nov 24, 2025

6 months ago

Claude Mythos Preview

—

Knowledge Cutoff

When training data ends

Claude Opus 4.5 has a documented knowledge cutoff of 2025-03-31, while Claude Mythos Preview's cutoff date is not specified.

We can confirm Claude Opus 4.5's training data extends to 2025-03-31, but cannot make a direct comparison without Claude Mythos Preview's cutoff date.

Claude Opus 4.5

Mar 2025

Claude Mythos Preview

—

Provider Availability

Claude Opus 4.5 is available from Anthropic. Claude Mythos Preview is available from Anthropic.

Claude Opus 4.5

anthropic logo
Anthropic
Input Price:Input: $5.00/1MOutput Price:Output: $25.00/1M

Claude Mythos Preview

anthropic logo
Anthropic
Input Price:Input: $25.00/1MOutput Price:Output: $125.00/1M
* Prices shown are per million tokens

Outputs Comparison

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Key Takeaways

Anthropic
Larger context window (200,000 tokens)
Less expensive input tokens
Less expensive output tokens
Anthropic
Higher GPQA score (94.6% vs 87.0%)
Higher MMMLU score (92.7% vs 90.8%)
Higher SWE-Bench Verified score (93.9% vs 80.9%)
Higher Terminal-Bench 2.0 score (82.0% vs 59.3%)

Detailed Comparison

AI Model Comparison Table
Feature
Anthropic
Claude Opus 4.5
Anthropic
Claude Mythos Preview

FAQ

Common questions about Claude Opus 4.5 vs Claude Mythos Preview.

Which is better, Claude Opus 4.5 or Claude Mythos Preview?

Claude Mythos Preview significantly outperforms across most benchmarks. Claude Opus 4.5 is made by Anthropic and Claude Mythos Preview is made by Anthropic. The best choice depends on your use case — compare their benchmark scores, pricing, and capabilities above.

How does Claude Opus 4.5 compare to Claude Mythos Preview in benchmarks?

Claude Opus 4.5 scores Tau2 Telecom: 98.2%, MMMLU: 90.8%, Tau2 Retail: 88.9%, GPQA: 87.0%, SWE-Bench Verified: 80.9%. Claude Mythos Preview scores CyBench: 100.0%, USAMO25: 97.6%, GPQA: 94.6%, SWE-Bench Verified: 93.9%, CharXiv-R: 93.2%.

Is Claude Opus 4.5 cheaper than Claude Mythos Preview?

Claude Opus 4.5 is 5.0x cheaper for input tokens. Claude Opus 4.5 costs $5.00/M input and $25.00/M output via anthropic. Claude Mythos Preview costs $25.00/M input and $125.00/M output via anthropic.

What are the context window sizes for Claude Opus 4.5 and Claude Mythos Preview?

Claude Opus 4.5 supports 200K tokens and Claude Mythos Preview supports an unknown number of tokens. A larger context window lets you process longer documents, conversations, or codebases in a single request.

What are the main differences between Claude Opus 4.5 and Claude Mythos Preview?

Key differences include input pricing ($5.00 vs $25.00/M). See the full comparison above for benchmark-by-benchmark results.

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