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Grok 4 Fast vs Grok-4 Heavy
Comprehensive side-by-side LLM comparison
Grok-4 Heavy leads with 3.4% higher average benchmark score. Both models have their strengths depending on your specific coding needs.
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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.
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xAI
Grok 4 Heavy was created as a larger, more capable variant of Grok 4, designed to provide maximum reasoning depth and analytical capability. Built for the most demanding applications requiring sophisticated problem-solving, it represents xAI's flagship offering in the fourth generation.
1 month newer
Grok-4 Heavy
xAI
2025-07-09
Grok 4 Fast
xAI
2025-08-28
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Performance Metrics
Context window and performance specifications
Average performance across 3 common benchmarks
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Grok 4 Fast
Average Score:85.9%
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Grok-4 Heavy
Average Score:89.3%(+3.4%)
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Knowledge Cutoff
Training data recency comparison
Grok-4 Heavy
2024-12-31
More recent knowledge cutoff means awareness of newer technologies and frameworks
Provider Availability & Performance
Available providers and their performance metrics
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Grok 4 Fast
1 providers
xAI
Throughput: 90 tok/s
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Grok-4 Heavy
0 providers
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Grok 4 Fast
Avg Score:85.9%
Providers:1
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Grok-4 Heavy
Avg Score:89.3%(+3.4%)
Providers:0