GPT-5.1 Codex High vs Grok 4 Fast: Specs & Benchmark Comparison
| Characteristic | GPT-5.1 Codex High | Grok 4 Fast |
|---|---|---|
| Company | OpenAI | xAI |
| Release Date | November 11, 2025 | August 27, 2025 |
| Parameters | — | — |
| Multimodal | Yes | Yes |
| Context (input) | 400K | 2.0M |
| Context (output) | 128K | 30K |
| Input Price / 1M | $1.25 | $0.20 |
| Output Price / 1M | $10.00 | $0.50 |
| Average Score | 1.0 | 0.8 |
| Benchmarks | ||
| AIME 2025 | 1.0 | 0.9 |
Visual Benchmark Comparison
GPT-5.1 Codex High
Grok 4 Fast
AIME 20251.0 vs 0.9
1.0
0.9
Verdict
Grok 4 Fast leads in 2 out of 4 comparison categories.
Overall Performance
Both models show comparable average scores: GPT-5.1 Codex High — 1.0, Grok 4 Fast — 0.8.
API Cost
Grok 4 Fast is 16.1x cheaper: input $0.20/1M vs $1.25/1M tokens.
Context Window
Grok 4 Fast supports a larger context: 2M vs 400K tokens.
Recency
GPT-5.1 Codex High is newer: released 11/11/2025 vs 8/27/2025.
More About These Models
Related Comparisons
Frequently Asked Questions
Which is better for coding — GPT-5.1 Codex High or Grok 4 Fast?
Direct comparison on the SWE-Bench benchmark is not available. We recommend reviewing other metrics on the comparison page.
Which model is cheaper — GPT-5.1 Codex High or Grok 4 Fast?
Grok 4 Fast is cheaper for input: $0.20 per 1M tokens vs $1.25.
Which has a larger context window — GPT-5.1 Codex High or Grok 4 Fast?
Grok 4 Fast supports a larger context: 2,000,000 tokens vs 400,000.
The GPT-5.1 Codex High and Grok 4 Fast comparison is updated for 2026. Data includes benchmark results, API pricing, context window size and other specifications. For more detailed information, visit the GPT-5.1 Codex High or Grok 4 Fast page. See also the complete list of AI model comparisons.