# GPT-5.3 Codex vs Grok-3 mini

> GPT-5.3 Codex is the stronger model overall, scoring 45.5 to 41.0 on the Noometry Index.

- Canonical page: https://noometry.com/compare/gpt-5-3-codex-vs-grok-3-mini
- Last updated: 2026-10-10
- Shared benchmarks: 2

## Summary

- They share 2 benchmarks with published results for both. GPT-5.3 Codex scores higher in 1 category and Grok-3 mini in 0 categories; one gap is clear of the uncertainty.
- The widest gap is in coding, where GPT-5.3 Codex leads 48.5 to 40.4.
- The biggest single-benchmark swing is WeirdML: 79.3% for GPT-5.3 Codex and 42.6% for Grok-3 mini.

## Snapshot

| | GPT-5.3 Codex | Grok-3 mini |
|---|---|---|
| Provider | OpenAI | xAI |
| Noometry Index | 45.5 | 41.0 |
| Rank | 61 | 130 |
| Context | 400K | — |
| Input $/M | $1.75 | — |
| Output $/M | $14 | — |
| Weights | Proprietary | Proprietary |

## Coding

- GPT-5.3 Codex: 48.5 (#51)
- Grok-3 mini: 40.4 (#126)

| Benchmark | GPT-5.3 Codex | Grok-3 mini |
|---|---|---|
| WeirdML | 79.3% | 42.6% |
| SWE-bench Verified | 74.8% | — |
| Aider Polyglot | — | 49.3% |
| LMArena WebDev | 1408 | — |
| LMArena Coding | — | 1380 |
| ALE-Bench | 1,655 | — |

## Agentic & Tool Use

- GPT-5.3 Codex: 47.8 (#9)
- Grok-3 mini: —

| Benchmark | GPT-5.3 Codex | Grok-3 mini |
|---|---|---|
| Terminal-Bench | 78.4% | — |
| METR Time Horizons | 74.5% | — |
| Vending-Bench 2 | 5,940 | — |

## Reasoning

- GPT-5.3 Codex: —
- Grok-3 mini: 13.8 (#323)

| Benchmark | GPT-5.3 Codex | Grok-3 mini |
|---|---|---|
| Epoch Capabilities Index | 156.84 | 140.35 |
| ARC-AGI-2 | — | 0.4% |
| Kagi LLM Benchmark | — | 61.3% |
| ARC-AGI-1 | — | 16.5% |
| LMArena Hard Prompts | — | 1374 |

## Math

- GPT-5.3 Codex: —
- Grok-3 mini: 40.3 (#78)

| Benchmark | GPT-5.3 Codex | Grok-3 mini |
|---|---|---|
| OTIS Mock AIME 2024-2025 | — | 77.8% |
| Omni-MATH | — | 31.8% |
| LMArena Math | — | 1386 |
| MATH Level 5 | — | 90.9% |
| FrontierMath (Feb 2025 set) | — | 5.9% |

## Knowledge

- GPT-5.3 Codex: —
- Grok-3 mini: 46.3 (#75)

| Benchmark | GPT-5.3 Codex | Grok-3 mini |
|---|---|---|
| GPQA Diamond | — | 76.3% |
| MMLU-Pro | — | 79.9% |
| Confabulations | — | 10.8% |
| GPQA (HELM) | — | 67.5% |
| LMArena Expert | — | 1395 |

## Multilingual

- GPT-5.3 Codex: —
- Grok-3 mini: 48.3 (#141)

| Benchmark | GPT-5.3 Codex | Grok-3 mini |
|---|---|---|
| LMArena Non-English | — | 1352 |
| LMArena Chinese | — | 1387 |
| LMArena French | — | 1357 |
| LMArena German | — | 1350 |
| LMArena Japanese | — | 1343 |
| LMArena Korean | — | 1336 |
| LMArena Russian | — | 1352 |
| LMArena Spanish | — | 1379 |

## Instruction Following

- GPT-5.3 Codex: —
- Grok-3 mini: 78.7 (#8)

| Benchmark | GPT-5.3 Codex | Grok-3 mini |
|---|---|---|
| IFEval | — | 95.1% |
| LMArena Instruction Following | — | 1356 |

## Long Context

- GPT-5.3 Codex: —
- Grok-3 mini: 41.0 (#142)

| Benchmark | GPT-5.3 Codex | Grok-3 mini |
|---|---|---|
| Fiction.LiveBench | — | 66.7% |
| LMArena Longer Query | — | 1372 |

## Writing & Preference

- GPT-5.3 Codex: —
- Grok-3 mini: 52.7 (#163)

| Benchmark | GPT-5.3 Codex | Grok-3 mini |
|---|---|---|
| LMArena Text | — | 1370 |
| LMArena Creative Writing | — | 1342 |
| Short-Story Creative Writing | — | 73.5% |
| WildBench | — | 65.1% |
| LMArena Multi-Turn | — | 1355 |

## FAQ

### Is GPT-5.3 Codex better than Grok-3 mini?

GPT-5.3 Codex is the stronger model overall, scoring 45.5 to 41.0 on the Noometry Index.

### Is GPT-5.3 Codex or Grok-3 mini better for coding?

GPT-5.3 Codex scores higher on coding benchmarks: 48.5 versus 40.4 in the Noometry coding category.

### How many benchmarks do GPT-5.3 Codex and Grok-3 mini share?

2 benchmarks have published results for both models. GPT-5.3 Codex has 8 scored results on Noometry and Grok-3 mini has 35.