Comprehensive side-by-side LLM comparison
Grok 4 Fast leads with 24.4% higher average benchmark score. Grok 4 Fast offers 1.9M more tokens in context window than GPT-4.5. Grok 4 Fast is $224.30 cheaper per million tokens. Overall, Grok 4 Fast is the stronger choice for coding tasks.
OpenAI
GPT-4.5 was developed as an intermediate advancement between GPT-4 and GPT-5, designed to incorporate incremental improvements in reasoning, factuality, and instruction-following. Built to bridge generational capabilities while maintaining compatibility with existing applications, it represents a refinement of the GPT-4 architecture with enhanced performance characteristics.
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.
6 months newer

GPT-4.5
OpenAI
2025-02-27

Grok 4 Fast
xAI
2025-08-28
Cost per million tokens (USD)

GPT-4.5

Grok 4 Fast
Context window and performance specifications
Average performance across 2 common benchmarks

GPT-4.5

Grok 4 Fast
Available providers and their performance metrics

GPT-4.5
OpenAI

Grok 4 Fast

GPT-4.5

Grok 4 Fast

GPT-4.5

Grok 4 Fast
xAI