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Claude Sonnet 4.5 vs Grok 4 Fast
Comprehensive side-by-side LLM comparison
Grok 4 Fast leads with 3.7% higher average benchmark score. Grok 4 Fast offers 1.8M more tokens in context window than Claude Sonnet 4.5. Grok 4 Fast is $17.30 cheaper per million tokens. Both models have their strengths depending on your specific coding needs.
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Anthropic
Claude Sonnet 4.5 was developed to bridge human thinking and machine assistance, allowing people to work with language and tools in a more conversational and natural way. Built with a focus on turning ideas into results, it represents an evolution in making AI feel less mechanical while maintaining strong capabilities across reasoning, coding, and collaborative tasks.
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xAI
Grok 4 Fast is a multimodal language model developed by xAI. It achieves strong performance with an average score of 73.0% across 7 benchmarks. It excels particularly in SimpleQA (95.0%), HMMT 2025 (93.3%), AIME 2025 (92.0%). With a 2.0M token context window, it can handle extensive documents and complex multi-turn conversations. The model is available through 1 API provider. As a multimodal model, it can process and understand text, images, and other input formats seamlessly. Released in 2025, it represents xAI's latest advancement in AI technology.
1 month newer
Grok 4 Fast
xAI
2025-08-28
Claude Sonnet 4.5
Anthropic
2025-09-29
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Pricing Comparison
Cost per million tokens (USD)
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Claude Sonnet 4.5
Input:$3.00
Output:$15.00
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Grok 4 Fast
Input:$0.20
Output:$0.50($17.30 cheaper)
Performance Metrics
Context window and performance specifications
Average performance across 2 common benchmarks
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Claude Sonnet 4.5
Average Score:85.2%
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Grok 4 Fast
Average Score:88.9%(+3.7%)
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Knowledge Cutoff
Training data recency comparison
Claude Sonnet 4.5
2025-01-31
More recent knowledge cutoff means awareness of newer technologies and frameworks
Provider Availability & Performance
Available providers and their performance metrics
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Claude Sonnet 4.5
2 providers
Anthropic
Throughput: 42 tok/s
Latency: 0.4ms
ZeroEval
Throughput: 42 tok/s
Latency: 0.4ms
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Claude Sonnet 4.5
Avg Score:85.2%
Providers:2
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Grok 4 Fast
Avg Score:88.9%(+3.7%)
Providers:1