Grok 3 Thinking vs xAI: Grok 4 Fast (free)
Compare Grok 3 Thinking and xAI: Grok 4 Fast (free), both from xAI, context windows of 128K vs 2.0M, tested across 14 shared challenges. Updated May 2026.
Which is better, Grok 3 Thinking or xAI: Grok 4 Fast (free)?
Grok 3 Thinking and xAI: Grok 4 Fast (free) are both competitive models. Context windows: 128K vs 2000K tokens. Compare their real outputs side by side below.
Key Differences Between Grok 3 Thinking and xAI: Grok 4 Fast (free)
Grok 3 Thinking is made by xai while xAI: Grok 4 Fast (free) is from xai. Grok 3 Thinking has a 128K token context window compared to xAI: Grok 4 Fast (free)'s 2000K.
API pricing
Per 1M tokens
Grok 3 Thinking
Input
—
Output
—
xAI: Grok 4 Fast (free)
Input
$0.000
Output
$0.000
Our Verdict
Grok 3 Thinking
xAI: Grok 4 Fast (free)
No community votes yet. On paper, these are closely matched - try both with your actual task to see which fits your workflow.
Too close to call
Writing DNA
Style Comparison
Similarity
52%
xAI: Grok 4 Fast (free) uses 2.5x more headings
Grok 3 Thinking
xAI: Grok 4 Fast (free)
46%Vocabulary65%
19wSentence Length13w
1.11Hedging0.56
3.3Bold1.4
2.6Lists2.5
0.00Emoji0.00
0.64Headings1.58
0.25Transitions0.28
Based on 6 + 14 text responses
FAQ
