# GPT-5-Codex vs Grok 4.3

> Grok 4.3 is the stronger model overall, scoring 43.8 to 37.9 on the Noometry Index.

- Canonical page: https://noometry.com/compare/gpt-5-codex-vs-grok-4-3
- Last updated: 2026-10-11
- Shared benchmarks: 1

## Summary

- They share 1 benchmark with published results for both. GPT-5-Codex scores higher in 2 categories and Grok 4.3 in 1 category; 2 gaps are clear of the uncertainty.
- The widest gap is in reasoning, where Grok 4.3 leads 35.9 to 30.9.
- Grok 4.3 is cheaper at $1.25 / $2.50 per million input/output tokens, against $1.25 / $10 for GPT-5-Codex.
- Grok 4.3 accepts more context: 1M tokens versus 400K.

## Snapshot

| | GPT-5-Codex | Grok 4.3 |
|---|---|---|
| Provider | OpenAI | xAI |
| Noometry Index | 37.9 | 43.8 |
| Rank | 192 | 86 |
| Context | 400K | 1M |
| Input $/M | $1.25 | $1.25 |
| Output $/M | $10 | $2.50 |
| Weights | Proprietary | Proprietary |

## Coding

- GPT-5-Codex: 42.4 (#103)
- Grok 4.3: 41.6 (#121)

| Benchmark | GPT-5-Codex | Grok 4.3 |
|---|---|---|
| WeirdML | 54.5% | 49.9% |
| LMArena WebDev | — | 1357 |
| SciCode | — | 47.3% |
| LMArena Coding | — | 1415 |
| ALE-Bench | — | 944.17 |

## Agentic & Tool Use

- GPT-5-Codex: 31.0 (#72)
- Grok 4.3: 27.7 (#99)

| Benchmark | GPT-5-Codex | Grok 4.3 |
|---|---|---|
| Terminal-Bench | 44.3% | — |
| GDP.pdf | — | 8% |
| LMArena Search | — | 1165 |
| Vending-Bench 2 | — | 35.26 |

## Reasoning

- GPT-5-Codex: 30.9 (#83)
- Grok 4.3: 35.9 (#68)

| Benchmark | GPT-5-Codex | Grok 4.3 |
|---|---|---|
| Kagi LLM Benchmark | 70.3% | — |
| NYT Connections (extended) | — | 55.2% |
| CritPt | — | 8% |
| Chess Puzzles | — | 25% |
| LMArena Hard Prompts | — | 1396 |
| DTBench | — | 90.7% |
| LMCA | — | 38.3% |
| Epoch Capabilities Index | — | 149.16 |
| ForecastBench | — | 60.3 |

## Math

- GPT-5-Codex: —
- Grok 4.3: 46.0 (#74)

| Benchmark | GPT-5-Codex | Grok 4.3 |
|---|---|---|
| FrontierMath (Tiers 1-3) | — | 42.8% |
| FrontierMath Tier 4 | — | 14.6% |
| OTIS Mock AIME 2024-2025 | — | 93.3% |
| ProofBench | — | 11% |
| LMArena Math | — | 1388 |

## Knowledge

- GPT-5-Codex: —
- Grok 4.3: 52.5 (#62)

| Benchmark | GPT-5-Codex | Grok 4.3 |
|---|---|---|
| GPQA Diamond | — | 88.8% |
| SimpleQA Verified | — | 33.2% |
| LMArena Expert | — | 1385 |

## Multimodal

- GPT-5-Codex: —
- Grok 4.3: 31.6 (#104)

| Benchmark | GPT-5-Codex | Grok 4.3 |
|---|---|---|
| LMArena Vision | — | 1229 |
| Blueprint-Bench 2 | — | 0% |

## Multilingual

- GPT-5-Codex: —
- Grok 4.3: 50.5 (#120)

| Benchmark | GPT-5-Codex | Grok 4.3 |
|---|---|---|
| LMArena Non-English | — | 1385 |
| LMArena Chinese | — | 1422 |
| LMArena French | — | 1412 |
| LMArena German | — | 1395 |
| LMArena Japanese | — | 1379 |
| LMArena Korean | — | 1356 |
| LMArena Russian | — | 1399 |
| LMArena Spanish | — | 1398 |

## Instruction Following

- GPT-5-Codex: —
- Grok 4.3: 72.1 (#140)

| Benchmark | GPT-5-Codex | Grok 4.3 |
|---|---|---|
| LMArena Instruction Following | — | 1366 |

## Long Context

- GPT-5-Codex: —
- Grok 4.3: 42.5 (#123)

| Benchmark | GPT-5-Codex | Grok 4.3 |
|---|---|---|
| LMArena Longer Query | — | 1393 |

## Writing & Preference

- GPT-5-Codex: —
- Grok 4.3: 58.5 (#118)

| Benchmark | GPT-5-Codex | Grok 4.3 |
|---|---|---|
| LMArena Text | — | 1397 |
| LMArena Creative Writing | — | 1380 |
| EQ-Bench 4 | — | 1075 |
| LMArena Multi-Turn | — | 1406 |

## FAQ

### Is GPT-5-Codex better than Grok 4.3?

Grok 4.3 is the stronger model overall, scoring 43.8 to 37.9 on the Noometry Index.

### Which is cheaper, GPT-5-Codex or Grok 4.3?

Grok 4.3 is cheaper. It lists at $1.25 per million input tokens and $2.50 per million output tokens; GPT-5-Codex lists at $1.25 and $10.

### Is GPT-5-Codex or Grok 4.3 better for coding?

They score almost the same on coding (42.4 vs 41.6); test both on your own repository before choosing.

### Which has the bigger context window?

Grok 4.3 does, with 1M tokens against 400K.

### How many benchmarks do GPT-5-Codex and Grok 4.3 share?

1 benchmark has published results for both models. GPT-5-Codex has 3 scored results on Noometry and Grok 4.3 has 40.