# GPT-5.3 Codex vs Grok 4.20

> Side-by-side benchmark comparison for GPT-5.3 Codex and Grok 4.20 across agentic, coding, multimodal, knowledge, reasoning, multilingual, and math tasks.

- Canonical page: https://benchlm.ai/compare/gpt-5-3-codex-vs-grok-4-20-beta
- Last updated: September 29, 2026

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

## Quick Verdict

Pick GPT-5.3 Codex if you want the stronger benchmark profile. Grok 4.20 only makes more sense when its price, context window, or workload-specific category wins matter more than the overall score.

## Summary

- GPT-5.3 Codex leads overall 61.81 to 59.74.
- The clearest category separation is in multimodal & grounded, where the averages are 76.7 for GPT-5.3 Codex and 35.6 for Grok 4.20.
- The biggest single benchmark swing is Vibe Code Bench in Coding, with scores of 61.77% and 4.06%.
- Grok 4.20 is the cheaper option on output tokens, which matters if you expect large responses or heavy interactive use.
- Grok 4.20 also has the larger context window at 2M.

## Model Snapshot

| Property | GPT-5.3 Codex | Grok 4.20 |
|----------|----------|----------|
| Creator | OpenAI | xAI |
| Type | Proprietary | Proprietary |
| Reasoning | Reasoning | Reasoning |
| Context | 400K | 2M |
| Overall Score | 61.81 | 59.74 |
| Benchmarks Covered | 10 | 23 |
| Pricing (input/output) | $1.75 / $14.00 | $1.25 / $2.50 |

## Category Breakdown

### Agentic

- Winner: Directional only
- GPT-5.3 Codex public-lane score: 54.1 (Estimated · #34/117)
- Grok 4.20 public-lane score: 23.3 (Supported · #95/117)

| Benchmark | GPT-5.3 Codex | Grok 4.20 | Winner |
|-----------|-----------|-----------|--------|
| Terminal-Bench 2.0 | 77.3% | 47.1% | GPT-5.3 Codex |
| OSWorld-Verified | 64.7% | Coming soon | Coming soon |
| Gert Labs | 57.47% | 38.36% | GPT-5.3 Codex |
| JobBench | 33.7% | Coming soon | Coming soon |
| DeepSearchQA | Coming soon | 62.8% | Coming soon |
| Terminal-Bench 2.1 (Vals) | Coming soon | 44.2% | Coming soon |

### Coding

- Winner: GPT-5.3 Codex
- GPT-5.3 Codex public-lane score: 55.5 (Supported · #29/143)
- Grok 4.20 public-lane score: 22.5 (Supported · #115/143)

| Benchmark | GPT-5.3 Codex | Grok 4.20 | Winner |
|-----------|-----------|-----------|--------|
| SWE-bench Verified | 85% | 76.7% | GPT-5.3 Codex |
| SWE-bench Pro | 56.8% | 51.8% | GPT-5.3 Codex |
| SWE-Rebench | 58.2% | Coming soon | Coming soon |
| Vibe Code Bench | 61.77% | 4.06% | GPT-5.3 Codex |
| LiveCodeBench (Vals) | 87.3% | 84.3% | GPT-5.3 Codex |
| SWE-bench (Vals) | 78.0% | 72.2% | GPT-5.3 Codex |
| LiveCodeBench Pro | Coming soon | 74.2% | Coming soon |

### Reasoning

- Winner: Not comparable
- GPT-5.3 Codex public-lane score: 79.6 (Unranked · 2 rankable rows)
- Grok 4.20 public-lane score: 41.1 (Unranked · 2 rankable rows)

| Benchmark | GPT-5.3 Codex | Grok 4.20 | Winner |
|-----------|-----------|-----------|--------|
| ARC-AGI-2 | Coming soon | 53.3% | Coming soon |
| ARC-AGI-3 | Coming soon | 0.1% | Coming soon |

### Multimodal & Grounded

- Winner: Not comparable
- GPT-5.3 Codex public-lane score: 76.7 (Unranked · 1 rankable row)
- Grok 4.20 public-lane score: 35.6 (#45/50)

| Benchmark | GPT-5.3 Codex | Grok 4.20 | Winner |
|-----------|-----------|-----------|--------|
| MMMU-Pro | Coming soon | 75.2% | Coming soon |
| CharXiv | Coming soon | 60.9% | Coming soon |
| ERQA | Coming soon | 54.1% | Coming soon |
| SimpleVQA | Coming soon | 57.4% | Coming soon |
| MedXpertQA (MM) | Coming soon | 65.8% | Coming soon |

### Knowledge

- Winner: Directional only
- GPT-5.3 Codex public-lane score: 63.8 (Estimated · #31/169)
- Grok 4.20 public-lane score: 49.2 (Supported · #64/169)

| Benchmark | GPT-5.3 Codex | Grok 4.20 | Winner |
|-----------|-----------|-----------|--------|
| GPQA-D | Coming soon | 88.5% | Coming soon |
| HLE w/o tools | Coming soon | 31.6% | Coming soon |
| HealthBench Hard | Coming soon | 20.3% | Coming soon |
| MedXpertQA (Text) | Coming soon | 50.2% | Coming soon |
| GPQA Diamond (Vals) | Coming soon | 88.6% | Coming soon |
| MMLU-Pro (Vals) | Coming soon | 86.3% | Coming soon |

### Instruction Following

- Winner: Not comparable
- GPT-5.3 Codex public-lane score: 91.2 (#14/124)
- Grok 4.20 public-lane score: Coming soon

## FAQ

### Which is better overall, GPT-5.3 Codex or Grok 4.20?

GPT-5.3 Codex is ahead overall on BenchLM right now.

### Where is the biggest gap between GPT-5.3 Codex and Grok 4.20?

The widest category gap is in multimodal & grounded, where the averages are 76.7 for GPT-5.3 Codex and 35.6 for Grok 4.20.

### How many benchmarks does GPT-5.3 Codex cover on BenchLM?

GPT-5.3 Codex currently has 10 sourced benchmark scores on BenchLM.

### How many benchmarks does Grok 4.20 cover on BenchLM?

Grok 4.20 currently has 23 sourced benchmark scores on BenchLM.

## Related Comparisons

- [GPT-5.3 Codex vs GPT-5.3-Codex-Spark](/compare/gpt-5-3-codex-vs-gpt-5-3-codex-spark)
- [Grok 4.20 vs GPT-5.3-Codex-Spark](/compare/gpt-5-3-codex-spark-vs-grok-4-20-beta)
- [GPT-5.3 Codex vs Grok 4.20 Multi-agent](/compare/gpt-5-3-codex-vs-grok-4-20-multi-agent-beta)
- [Grok 4.20 vs Grok 4.20 Multi-agent](/compare/grok-4-20-beta-vs-grok-4-20-multi-agent-beta)

## Explore More

- [GPT-5.3 Codex profile](/models/gpt-5-3-codex)
- [Grok 4.20 profile](/models/grok-4-20-beta)
- [Compare Pricing](/llm-pricing)
- [Alternative Finder](/tools/alternative-finder)
- [LLM Selector](/tools/llm-selector)
- [Overall Rankings](/best/overall)