GPT-5 vs xAI: Grok 4 Fast (free)
Compare GPT-5 by OpenAI against xAI: Grok 4 Fast (free) by xAI, context windows of 400K vs 2.0M, tested across 34 shared challenges. Updated May 2026.
Which is better, GPT-5 or xAI: Grok 4 Fast (free)?
GPT-5 and xAI: Grok 4 Fast (free) are both competitive models. GPT-5 costs $1.25/M input tokens vs $0/M for xAI: Grok 4 Fast (free). Context windows: 400K vs 2000K tokens. Compare their real outputs side by side below.
Key Differences Between GPT-5 and xAI: Grok 4 Fast (free)
GPT-5 is made by openai while xAI: Grok 4 Fast (free) is from xai. GPT-5 has a 400K token context window compared to xAI: Grok 4 Fast (free)'s 2000K. On pricing, GPT-5 costs $1.25/M input tokens vs $0/M for xAI: Grok 4 Fast (free).
Per 1M tokens
No community votes yet. On paper, these are closely matched - try both with your actual task to see which fits your workflow.
Style Comparison
xAI: Grok 4 Fast (free) uses 10.0x more transitions
