Model Comparison

Claude Sonnet 4.5 vs Grok Code Fast 1Which is better in 2026?

Comparing Claude Sonnet 4.5 and Grok Code Fast 1 across benchmarks, pricing, and capabilities.

Verdict: Claude Sonnet 4.5 vs Grok Code Fast 1 — which is better?

Claude Sonnet 4.5 (by Anthropic) and Grok Code Fast 1 (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.

On price, Grok Code Fast 1 is roughly 11.4x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.

Grok Code Fast 1 also accepts a larger context window (256,000 input tokens), making it the stronger choice for long documents and large codebases.

Choose Claude Sonnet 4.5 if…

  • you want the most recent training data — it shipped Sep 2025

Choose Grok Code Fast 1 if…

  • cost matters — it's about 11.4x cheaper per token
  • you process long inputs — it offers a 256,000 token context window

Performance Benchmarks

Comparative analysis across standard metrics

No common benchmarks found

Claude Sonnet 4.5 and Grok Code Fast 1don't have any common benchmark datasets to compare. They may have been evaluated on different testing suites.

Arena Performance

Human preference votes

Pricing Analysis

Price comparison per million tokens

Grok Code Fast 1 costs less

For input processing, Claude Sonnet 4.5 ($3.00/1M tokens) is 15.0x more expensive than Grok Code Fast 1 ($0.20/1M tokens).

For output processing, Claude Sonnet 4.5 ($15.00/1M tokens) is 10.0x more expensive than Grok Code Fast 1 ($1.50/1M tokens).

In conclusion, Claude Sonnet 4.5 is more expensive than Grok Code Fast 1.*

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

Lowest available price from all providers
Tue Jul 28 2026 • llm-stats.com
Anthropic
Claude Sonnet 4.5
Input tokens$3.00
Output tokens$15.00
Best providerAnthropic
xAI
Grok Code Fast 1
Input tokens$0.20
Output tokens$1.50
Best providerxAI
Notice missing or incorrect data?Start an Issue→

Context Window

Maximum input and output token capacity

Grok Code Fast 1 accepts 256,000 input tokens compared to Claude Sonnet 4.5's 200,000 tokens. Claude Sonnet 4.5 can generate longer responses up to 64,000 tokens, while Grok Code Fast 1 is limited to 10,000 tokens.

Anthropic
Claude Sonnet 4.5
Input200,000 tokens
Output64,000 tokens
xAI
Grok Code Fast 1
Input256,000 tokens
Output10,000 tokens
Tue Jul 28 2026 • llm-stats.com

Input Capabilities

Supported data types and modalities

Claude Sonnet 4.5 supports multimodal inputs, whereas Grok Code Fast 1 does not.

Claude Sonnet 4.5 can handle both text and other forms of data like images, making it suitable for multimodal applications.

Claude Sonnet 4.5

Text
Images
Audio
Video

Grok Code Fast 1

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 Sonnet 4.5

Proprietary

Closed source

Grok Code Fast 1

Proprietary

Closed source

Release Timeline

When each model was launched

Claude Sonnet 4.5 was released on 2025-09-29, while Grok Code Fast 1 was released on 2025-08-28.

Claude Sonnet 4.5 is 1 month newer than Grok Code Fast 1.

Claude Sonnet 4.5

Sep 29, 2025

10 months ago

1mo newer
Grok Code Fast 1

Aug 28, 2025

11 months ago

Knowledge Cutoff

When training data ends

Claude Sonnet 4.5 has a documented knowledge cutoff of 2025-01-31, while Grok Code Fast 1's cutoff date is not specified.

We can confirm Claude Sonnet 4.5's training data extends to 2025-01-31, but cannot make a direct comparison without Grok Code Fast 1's cutoff date.

Claude Sonnet 4.5

Jan 2025

Grok Code Fast 1

—

Provider Availability

Claude Sonnet 4.5 is available from Anthropic. Grok Code Fast 1 is available from xAI.

Claude Sonnet 4.5

anthropic logo
Anthropic
Input Price:Input: $3.00/1MOutput Price:Output: $15.00/1M

Grok Code Fast 1

xai logo
xAI
Input Price:Input: $0.20/1MOutput Price:Output: $1.50/1M
* Prices shown are per million tokens

Outputs Comparison

Notice missing or incorrect data?Start an Issue discussion→

Key Takeaways

Anthropic
Supports multimodal inputs
xAI
Larger context window (256,000 tokens)
Less expensive input tokens
Less expensive output tokens

Detailed Comparison

Interactive Arena

Judge for yourself.

Run your own prompts against Claude Sonnet 4.5 and Grok Code Fast 1 side-by-side, then vote on the output you prefer.

Claude Sonnet 4.5
✓ Preferred
Grok Code Fast 1
Open in Playground
AI Model Comparison Table
Feature
Anthropic
Claude Sonnet 4.5
xAI
Grok Code Fast 1

FAQ

Common questions about Claude Sonnet 4.5 vs Grok Code Fast 1.

Which is better, Claude Sonnet 4.5 or Grok Code Fast 1?

Claude Sonnet 4.5 (Anthropic) and Grok Code Fast 1 (xAI) each have strengths in different areas. Compare their benchmark scores, pricing, context windows, and capabilities above to determine which fits your needs.

How does Claude Sonnet 4.5 compare to Grok Code Fast 1 in benchmarks?

Claude Sonnet 4.5 scores MMMLU: 89.1%, AIME 2025: 87.0%, TAU-bench Retail: 86.2%, GPQA: 83.4%, MMMUval: 77.8%. Grok Code Fast 1 scores SWE-Bench Verified: 70.8%.

Is Claude Sonnet 4.5 cheaper than Grok Code Fast 1?

Grok Code Fast 1 is 15.0x cheaper for input tokens. Claude Sonnet 4.5 costs $3.00/M input and $15.00/M output via anthropic. Grok Code Fast 1 costs $0.20/M input and $1.50/M output via xai.

What are the context window sizes for Claude Sonnet 4.5 and Grok Code Fast 1?

Claude Sonnet 4.5 supports 200K tokens and Grok Code Fast 1 supports 256K tokens. A larger context window lets you process longer documents, conversations, or codebases in a single request.

What are the main differences between Claude Sonnet 4.5 and Grok Code Fast 1?

Key differences include context window (200K vs 256K), input pricing ($3.00 vs $0.20/M), multimodal support (yes vs no). See the full comparison above for benchmark-by-benchmark results.

Who makes Claude Sonnet 4.5 and Grok Code Fast 1?

Claude Sonnet 4.5 is developed by Anthropic and Grok Code Fast 1 is developed by xAI.

Related comparisons