Claude Opus 4.1 vs Grok-4 Fast Reasoning Comparison

Comparing Claude Opus 4.1 and Grok-4 Fast Reasoning across benchmarks, pricing, and capabilities.

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Performance Benchmarks

Comparative analysis across standard metrics

No common benchmarks found

Claude Opus 4.1 and Grok-4 Fast Reasoning don'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-4 Fast Reasoning costs less

For input processing, Claude Opus 4.1 ($15.00/1M tokens) is 75.0x more expensive than Grok-4 Fast Reasoning ($0.20/1M tokens).

For output processing, Claude Opus 4.1 ($75.00/1M tokens) is 150.0x more expensive than Grok-4 Fast Reasoning ($0.50/1M tokens).

In conclusion, Claude Opus 4.1 is more expensive than Grok-4 Fast Reasoning.*

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

Lowest available price from all providers

Tue Mar 17 2026 • llm-stats.com

Claude Opus 4.1

Input tokens$15.00

Output tokens$75.00

Best providerAnthropic

Grok-4 Fast Reasoning

Input tokens$0.20

Output tokens$0.50

Best providerxAI

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Context Window

Maximum input and output token capacity

Grok-4 Fast Reasoning accepts 2,000,000 input tokens compared to Claude Opus 4.1's 200,000 tokens. Claude Opus 4.1 can generate longer responses up to 32,000 tokens, while Grok-4 Fast Reasoning is limited to 30,000 tokens.

Claude Opus 4.1

Input200,000 tokens

Output32,000 tokens

Grok-4 Fast Reasoning

Input2,000,000 tokens

Output30,000 tokens

Tue Mar 17 2026 • llm-stats.com

Input Capabilities

Supported data types and modalities

Both Claude Opus 4.1 and Grok-4 Fast Reasoning support multimodal inputs.

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

Claude Opus 4.1

Text

Images

Audio

Video

Grok-4 Fast Reasoning

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 4.1

Proprietary

Closed source

Grok-4 Fast Reasoning

Proprietary

Closed source

Release Timeline

When each model was launched

Claude Opus 4.1 was released on 2025-08-05, while Grok-4 Fast Reasoning was released on 2025-08-28.

Grok-4 Fast Reasoning is 1 month newer than Claude Opus 4.1.

Claude Opus 4.1

Aug 5, 2025

7 months ago

Grok-4 Fast Reasoning

Aug 28, 2025

6 months ago

3w newer

Knowledge Cutoff

When training data ends

Neither model specifies a knowledge cutoff date.

Unable to compare the recency of their training data.

No cutoff dates available

Provider Availability

Claude Opus 4.1 is available from Anthropic, Bedrock, Google. Grok-4 Fast Reasoning is available from xAI. The availability of providers can affect quality of the model and reliability.