Grok 4 Fast vs Grok-4 Heavy: Specs & Benchmark Comparison
| Characteristic | Grok 4 Fast | Grok-4 Heavy |
|---|---|---|
| Company | xAI | xAI |
| Release Date | August 27, 2025 | July 8, 2025 |
| Parameters | — | — |
| Multimodal | Yes | Yes |
| Context (input) | 2.0M | — |
| Context (output) | 30K | — |
| Input Price / 1M | $0.20 | — |
| Output Price / 1M | $0.50 | — |
| Average Score | 0.8 | 0.8 |
| Benchmarks | ||
| AIME 2025 | 0.9 | 1.0 |
| GPQA | 0.9 | 0.9 |
| LiveCodeBench | 0.8 | 0.8 |
Visual Benchmark Comparison
Grok 4 Fast
Grok-4 Heavy
AIME 20250.9 vs 1.0
0.9
1.0
GPQA0.9 vs 0.9
0.9
0.9
LiveCodeBench0.8 vs 0.8
0.8
0.8
Verdict
Grok 4 Fast leads in 1 out of 2 comparison categories.
Overall Performance
Both models show comparable average scores: Grok 4 Fast — 0.8, Grok-4 Heavy — 0.8.
Recency
Grok 4 Fast is newer: released 8/27/2025 vs 7/8/2025.
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Frequently Asked Questions
Which is better for coding — Grok 4 Fast or Grok-4 Heavy?
Direct comparison on the SWE-Bench benchmark is not available. We recommend reviewing other metrics on the comparison page.
Which model is cheaper — Grok 4 Fast or Grok-4 Heavy?
API pricing data is available on the individual model pages.
Which has a larger context window — Grok 4 Fast or Grok-4 Heavy?
Context window data is available on the individual model pages.
The Grok 4 Fast and Grok-4 Heavy comparison is updated for 2026. Data includes benchmark results, API pricing, context window size and other specifications. For more detailed information, visit the Grok 4 Fast or Grok-4 Heavy page. See also the complete list of AI model comparisons.