# GPT-5.1-Codex vs Grok Code Fast 1

> Side-by-side benchmark comparison for GPT-5.1-Codex and Grok Code Fast 1 across agentic, coding, multimodal, knowledge, reasoning, multilingual, and math tasks.

- Canonical page: https://benchlm.ai/compare/gpt-5-1-codex-vs-grok-code-fast-1
- Last updated: September 29, 2026

- Shared sourced benchmarks: 1
- HTML indexing: indexable
- Ranking lane: BenchAlign v5.7

## Quick Verdict

Evidence is too thin for a benchmark verdict: GPT-5.1-Codex and Grok Code Fast 1 share only 1 sourced benchmark row.

## Summary

- Only 1 shared sourced benchmark row is available. That is not enough for a broad capability verdict, so this mirror does not name an overall winner.
- Grok Code Fast 1 has the lower published output-token price.
- GPT-5.1-Codex has the larger published context window at 400K.

## Model Snapshot

| Property | GPT-5.1-Codex | Grok Code Fast 1 |
|----------|----------|----------|
| Creator | OpenAI | xAI |
| Type | Proprietary | Proprietary |
| Reasoning | Reasoning | Non-Reasoning |
| Context | 400K | 256K |
| Independent public score (not head-to-head) | 44.38 | 31.94 |
| Benchmarks Covered | 4 | 2 |
| Pricing (input/output) | $1.25 / $10.00 | $0.20 / $1.50 |

## Category Breakdown

### Agentic

- Winner: Insufficient shared evidence
- GPT-5.1-Codex public-lane score: Coming soon
- Grok Code Fast 1 public-lane score: Coming soon

| Benchmark | GPT-5.1-Codex | Grok Code Fast 1 | Winner |
|-----------|-----------|-----------|--------|
| Gert Labs | 49.68% | Coming soon | Coming soon |
| JobBench | 26.2% | Coming soon | Coming soon |

### Coding

- Winner: Insufficient shared evidence
- GPT-5.1-Codex public-lane score: 32.7 (Estimated · #85/143)
- Grok Code Fast 1 public-lane score: 21.5 (Estimated · #119/143)

| Benchmark | GPT-5.1-Codex | Grok Code Fast 1 | Winner |
|-----------|-----------|-----------|--------|
| Vibe Code Bench | 13.12% | Coming soon | Coming soon |
| LiveCodeBench (Vals) | 85.6% | 62.0% | GPT-5.1-Codex |
| SWE-bench Verified | Coming soon | 70.8% | Coming soon |

### Reasoning

- Winner: Insufficient shared evidence
- GPT-5.1-Codex public-lane score: 69.9 (Unranked · 2 rankable rows)
- Grok Code Fast 1 public-lane score: 58.7 (Unranked · 2 rankable rows)

### Multimodal & Grounded

- Winner: Insufficient shared evidence
- GPT-5.1-Codex public-lane score: 67.9 (Unranked · 1 rankable row)
- Grok Code Fast 1 public-lane score: Coming soon

### Knowledge

- Winner: Insufficient shared evidence
- GPT-5.1-Codex public-lane score: 48.1 (Estimated · #69/169)
- Grok Code Fast 1 public-lane score: 36 (Estimated · #112/169)

### Instruction Following

- Winner: Insufficient shared evidence
- GPT-5.1-Codex public-lane score: 84.2 (#42/124)
- Grok Code Fast 1 public-lane score: 46.8 (#87/124)

## FAQ

### Is there enough evidence to pick between GPT-5.1-Codex and Grok Code Fast 1?

Not yet. The models share only 1 sourced benchmark row, so this mirror reports the available measurements and metadata without naming a broad winner.

### What can I compare safely on this page?

Published pricing, context windows, model type, and individual shared benchmark rows are directly comparable. Independent overall scores and non-overlapping benchmark coverage are labeled separately and should not be read as a controlled head-to-head result.

## Related Comparisons

- [GPT-5.1-Codex vs GPT-6 Astra](/compare/gpt-5-1-codex-vs-gpt-6-astra)
- [Grok Code Fast 1 vs GPT-6 Astra](/compare/gpt-6-astra-vs-grok-code-fast-1)
- [GPT-5.1-Codex vs Claude Opus 5.5](/compare/claude-opus-5-5-vs-gpt-5-1-codex)
- [Grok Code Fast 1 vs Claude Opus 5.5](/compare/claude-opus-5-5-vs-grok-code-fast-1)

## Explore More

- [GPT-5.1-Codex profile](/models/gpt-5-1-codex)
- [Grok Code Fast 1 profile](/models/grok-code-fast-1)
- [Compare Pricing](/llm-pricing)
- [Alternative Finder](/tools/alternative-finder)
- [LLM Selector](/tools/llm-selector)
- [Overall Rankings](/best/overall)