Grok 4 Fast vs Kimi K2.5: Specs & Benchmark Comparison
| Characteristic | Grok 4 Fast | Kimi K2.5 |
|---|---|---|
| Company | xAI | Moonshot AI |
| Release Date | August 27, 2025 | January 26, 2026 |
| Parameters | — | 1.0T |
| Multimodal | Yes | Yes |
| Context (input) | 2.0M | — |
| Context (output) | 30K | — |
| Input Price / 1M | $0.20 | — |
| Output Price / 1M | $0.50 | — |
| Average Score | 0.8 | 0.9 |
| Benchmarks | ||
| AIME 2025 | 0.9 | 1.0 |
| HMMT 2025 | 0.9 | 0.9 |
| GPQA | 0.9 | 0.9 |
Visual Benchmark Comparison
Grok 4 Fast
Kimi K2.5
AIME 20250.9 vs 1.0
0.9
1.0
HMMT 20250.9 vs 0.9
0.9
0.9
GPQA0.9 vs 0.9
0.9
0.9
Verdict
Kimi K2.5 leads in 1 out of 2 comparison categories.
Overall Performance
Both models show comparable average scores: Grok 4 Fast — 0.8, Kimi K2.5 — 0.9.
Recency
Kimi K2.5 is newer: released 1/26/2026 vs 8/27/2025.
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Frequently Asked Questions
Which is better for coding — Grok 4 Fast or Kimi K2.5?
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 Kimi K2.5?
API pricing data is available on the individual model pages.
Which has a larger context window — Grok 4 Fast or Kimi K2.5?
Context window data is available on the individual model pages.
The Grok 4 Fast and Kimi K2.5 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 Kimi K2.5 page. See also the complete list of AI model comparisons.