Model Comparison

Claude Mythos Preview vs Grok 4.5Which is better in 2026?

Claude Mythos Preview significantly outperforms across most benchmarks. Grok 4.5 is 16.7x cheaper per token.

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

Claude Mythos Preview (by Anthropic) and Grok 4.5 (by xAI) 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 Mythos Preview outperforms in 2 benchmarks (GPQA, SWE-Bench Pro), while Grok 4.5 is better at 0 benchmarks. Claude Mythos Preview significantly outperforms across most benchmarks.

On price, Grok 4.5 is roughly 16.7x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.

Choose Claude Mythos Preview if…

  • you want the strongest raw capability — it leads on 2 of 2 shared benchmarks

Choose Grok 4.5 if…

  • cost matters — it's about 16.7x cheaper per token

Performance Benchmarks

Comparative analysis across standard metrics

2 benchmarks

Claude Mythos Preview outperforms in 2 benchmarks (GPQA, SWE-Bench Pro), while Grok 4.5 is better at 0 benchmarks.

Claude Mythos Preview significantly outperforms across most benchmarks.

Wed Jul 22 2026 • llm-stats.com

Arena Performance

Human preference votes

Pricing Analysis

Price comparison per million tokens

Grok 4.5 costs less

For input processing, Claude Mythos Preview ($25.00/1M tokens) is 12.5x more expensive than Grok 4.5 ($2.00/1M tokens).

For output processing, Claude Mythos Preview ($125.00/1M tokens) is 20.8x more expensive than Grok 4.5 ($6.00/1M tokens).

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

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

Lowest available price from all providers
Wed Jul 22 2026 • llm-stats.com
Anthropic
Claude Mythos Preview
Input tokens$25.00
Output tokens$125.00
Best providerAnthropic
xAI
Grok 4.5
Input tokens$2.00
Output tokens$6.00
Best providerxAI
Notice missing or incorrect data?Start an Issue→

Context Window

Maximum input and output token capacity

Only Grok 4.5 specifies input context (500,000 tokens).

Anthropic
Claude Mythos Preview
Input- tokens
Output- tokens
xAI
Grok 4.5
Input500,000 tokens
Output- tokens
Wed Jul 22 2026 • llm-stats.com

Input Capabilities

Supported data types and modalities

Both Claude Mythos Preview and Grok 4.5 support multimodal inputs.

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

Claude Mythos Preview

Text
Images
Audio
Video

Grok 4.5

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 Mythos Preview

Proprietary

Closed source

Grok 4.5

Proprietary

Closed source

Release Timeline

When each model was launched

Grok 4.5 was released on 2026-07-16, while Claude Mythos Preview's release date is not specified.

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

Claude Mythos Preview

—

Grok 4.5

Jul 16, 2026

5 days ago

Knowledge Cutoff

When training data ends

Grok 4.5 has a documented knowledge cutoff of 2026-02-01, while Claude Mythos Preview's cutoff date is not specified.

We can confirm Grok 4.5's training data extends to 2026-02-01, but cannot make a direct comparison without Claude Mythos Preview's cutoff date.

Claude Mythos Preview

—

Grok 4.5

Feb 2026

Provider Availability

Claude Mythos Preview is available from Anthropic. Grok 4.5 is available from xAI.

Claude Mythos Preview

anthropic logo
Anthropic
Input Price:Input: $25.00/1MOutput Price:Output: $125.00/1M

Grok 4.5

xai logo
xAI
Input Price:Input: $2.00/1MOutput Price:Output: $6.00/1M
* Prices shown are per million tokens

Outputs Comparison

Notice missing or incorrect data?Start an Issue discussion→

Key Takeaways

Anthropic
Higher GPQA score (94.6% vs 93.0%)
Higher SWE-Bench Pro score (77.8% vs 64.7%)
xAI
Larger context window (500,000 tokens)
Less expensive input tokens
Less expensive output tokens

Detailed Comparison

Interactive Arena

Judge for yourself.

Run your own prompts against Claude Mythos Preview and Grok 4.5 side-by-side, then vote on the output you prefer.

Claude Mythos Preview
✓ Preferred
Grok 4.5
Open in Playground
AI Model Comparison Table
Feature
Anthropic
Claude Mythos Preview
xAI
Grok 4.5

FAQ

Common questions about Claude Mythos Preview vs Grok 4.5.

Which is better, Claude Mythos Preview or Grok 4.5?

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

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

Claude Mythos Preview scores CyBench: 100.0%, USAMO25: 97.6%, GPQA: 94.6%, SWE-Bench Verified: 93.9%, CharXiv-R: 93.2%. Grok 4.5 scores GPQA: 93.0%, Terminal-Bench 2.1: 83.3%, Artificial Analysis Coding Agent Index v1.1: 76.0%, SWE-Bench Pro: 64.7%, AA-Omniscience Index: 63.0%.

Is Claude Mythos Preview cheaper than Grok 4.5?

Grok 4.5 is 12.5x cheaper for input tokens. Claude Mythos Preview costs $25.00/M input and $125.00/M output via anthropic. Grok 4.5 costs $2.00/M input and $6.00/M output via xai.

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

Claude Mythos Preview supports an unknown number of tokens and Grok 4.5 supports 500K tokens. A larger context window lets you process longer documents, conversations, or codebases in a single request.

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

Key differences include input pricing ($25.00 vs $2.00/M). See the full comparison above for benchmark-by-benchmark results.

Who makes Claude Mythos Preview and Grok 4.5?

Claude Mythos Preview is developed by Anthropic and Grok 4.5 is developed by xAI.

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