# GPT-5.3 Codex vs Grok Code Fast 1

> Side-by-side benchmark comparison for GPT-5.3 Codex and Grok Code Fast 1 across agentic, coding, multimodal, knowledge, reasoning, multilingual, and math tasks.

- Canonical page: https://benchlm.ai/compare/gpt-5-3-codex-vs-grok-code-fast-1
- Last updated: October 17, 2026

- Shared sourced benchmarks: 2
- HTML indexing: indexable
- Ranking lane: BenchAlign v5.8

## Quick Verdict

Evidence is too thin for a benchmark verdict: GPT-5.3 Codex and Grok Code Fast 1 share only 2 sourced benchmark rows.

## Summary

- Only 2 shared sourced benchmark rows are 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-5.3 Codex has the larger published context window at 400K.

## Model Snapshot

| Property | GPT-5.3 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) | 60.48 | 34.09 |
| Benchmarks Covered | 11 | 2 |
| Pricing (input/output) | $1.75 / $14.00 | $0.20 / $1.50 |

## Category Breakdown

### Agentic

- Winner: Insufficient shared evidence
- GPT-5.3 Codex public-lane score: 55.5 (Estimated · #41/128)
- Grok Code Fast 1 public-lane score: Coming soon

| Benchmark | GPT-5.3 Codex | Grok Code Fast 1 | Winner |
|-----------|-----------|-----------|--------|
| Terminal-Bench 2.0 | 77.3% | Coming soon | Coming soon |
| OSWorld-Verified | 64.7% | Coming soon | Coming soon |
| Gert Labs | 57.47% | Coming soon | Coming soon |
| JobBench | 33.7% | Coming soon | Coming soon |

### Coding

- Winner: Insufficient shared evidence
- GPT-5.3 Codex public-lane score: 53.5 (Supported · #35/150)
- Grok Code Fast 1 public-lane score: 16.7 (Estimated · #127/150)

| Benchmark | GPT-5.3 Codex | Grok Code Fast 1 | Winner |
|-----------|-----------|-----------|--------|
| SWE-bench Verified | 85% | 70.8% | GPT-5.3 Codex |
| SWE-bench Pro | 56.8% | Coming soon | Coming soon |
| SWE-Rebench | 58.2% | Coming soon | Coming soon |
| Terminal-Bench 2.0 | 77.3% | Coming soon | Coming soon |
| Vibe Code Bench | 61.77% | Coming soon | Coming soon |
| LiveCodeBench (Vals) | 87.3% | 62.0% | GPT-5.3 Codex |
| SWE-bench (Vals) | 78.0% | Coming soon | Coming soon |

### Reasoning

- Winner: Insufficient shared evidence
- GPT-5.3 Codex public-lane score: 83.1 (Unranked · 2 rankable rows)
- Grok Code Fast 1 public-lane score: 62.3 (Unranked · 2 rankable rows)

### Multimodal & Grounded

- Winner: Insufficient shared evidence
- GPT-5.3 Codex public-lane score: 80.1 (Unranked · 1 rankable row)
- Grok Code Fast 1 public-lane score: Coming soon

### Knowledge

- Winner: Insufficient shared evidence
- GPT-5.3 Codex public-lane score: 65.4 (Estimated · #33/184)
- Grok Code Fast 1 public-lane score: 35.9 (Estimated · #131/184)

### Instruction Following

- Winner: Insufficient shared evidence
- GPT-5.3 Codex public-lane score: 92.6 (#18/148)
- Grok Code Fast 1 public-lane score: 48.2 (#98/148)

## FAQ

### Is there enough evidence to pick between GPT-5.3 Codex and Grok Code Fast 1?

Not yet. The models share only 2 sourced benchmark rows, 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-5.3 Codex vs GPT-5.3-Codex-Spark](/compare/gpt-5-3-codex-vs-gpt-5-3-codex-spark)
- [Grok Code Fast 1 vs GPT-5.3-Codex-Spark](/compare/gpt-5-3-codex-spark-vs-grok-code-fast-1)
- [GPT-5.3 Codex vs Claude Opus 5.5](/compare/claude-opus-5-5-vs-gpt-5-3-codex)
- [Grok Code Fast 1 vs Claude Opus 5.5](/compare/claude-opus-5-5-vs-grok-code-fast-1)

## Explore More

- [GPT-5.3 Codex profile](/models/gpt-5-3-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)