# GPT-5.3 Chat vs Grok 4.5

> Grok 4.5 is the stronger model overall, scoring 55.0 to 42.8 on the Noometry Index.

- Canonical page: https://noometry.com/compare/gpt-5-3-chat-vs-grok-4-5
- Last updated: 2026-10-12
- Shared benchmarks: 18

## Summary

- They share 18 benchmarks with published results for both. GPT-5.3 Chat scores higher in 0 categories and Grok 4.5 in 8 categories; 8 gaps are clear of the uncertainty.
- The widest gap is in reasoning, where Grok 4.5 leads 56.1 to 28.5.
- Grok 4.5 is cheaper at $2 / $6 per million input/output tokens, against $1.75 / $14 for GPT-5.3 Chat.
- Grok 4.5 accepts more context: 500K tokens versus 128K.

## Snapshot

| | GPT-5.3 Chat | Grok 4.5 |
|---|---|---|
| Provider | OpenAI | xAI |
| Noometry Index | 42.8 | 55.0 |
| Rank | 109 | 25 |
| Context | 128K | 500K |
| Input $/M | $1.75 | $2 |
| Output $/M | $14 | $6 |
| Weights | Proprietary | Proprietary |

## Coding

- GPT-5.3 Chat: 41.4 (#124)
- Grok 4.5: 52.2 (#35)

| Benchmark | GPT-5.3 Chat | Grok 4.5 |
|---|---|---|
| LMArena Coding | 1408 | 1474 |
| DeepSWE | — | 53.8% |
| FrontierCode | — | 42.4% |
| LMArena WebDev | — | 1553 |
| SciCode | — | 54.1% |
| WeirdML | — | 46.4% |
| ALE-Bench | — | 1,309 |

## Agentic & Tool Use

- GPT-5.3 Chat: —
- Grok 4.5: 44.4 (#17)

| Benchmark | GPT-5.3 Chat | Grok 4.5 |
|---|---|---|
| APEX-Agents | — | 56.2% |
| τ²-bench Banking | — | 47.9% |
| PostTrainBench | — | 23.4% |
| GBAEval | — | 65.4% |
| GDP.pdf | — | 14% |
| LMArena Search | — | 1213 |
| Vending-Bench 2 | — | 3,887 |

## Reasoning

- GPT-5.3 Chat: 28.5 (#102)
- Grok 4.5: 56.1 (#25)

| Benchmark | GPT-5.3 Chat | Grok 4.5 |
|---|---|---|
| LMArena Hard Prompts | 1399 | 1462 |
| ARC-AGI-2 | — | 52.6% |
| SimpleBench | — | 70% |
| Kagi LLM Benchmark | — | 83.5% |
| NYT Connections (extended) | — | 79.9% |
| ARC-AGI-1 | — | 87.2% |
| CritPt | — | 15.4% |
| Chess Puzzles | — | 36% |
| DTBench | — | 96.5% |
| LMCA | — | 45.2% |
| Surface Evolver Bench | — | 74.4% |
| Epoch Capabilities Index | — | 153.92 |

## Math

- GPT-5.3 Chat: 38.2 (#142)
- Grok 4.5: 60.9 (#35)

| Benchmark | GPT-5.3 Chat | Grok 4.5 |
|---|---|---|
| LMArena Math | 1389 | 1459 |
| FrontierMath (Tiers 1-3) | — | 57.2% |
| FrontierMath Tier 4 | — | 24.4% |
| OTIS Mock AIME 2024-2025 | — | 97.8% |
| ProofBench | — | 31% |

## Knowledge

- GPT-5.3 Chat: 38.8 (#140)
- Grok 4.5: 62.3 (#24)

| Benchmark | GPT-5.3 Chat | Grok 4.5 |
|---|---|---|
| LMArena Expert | 1397 | 1466 |
| GPQA Diamond | — | 93.4% |
| SimpleQA Verified | — | 48.3% |

## Multimodal

- GPT-5.3 Chat: —
- Grok 4.5: 37.6 (#72)

| Benchmark | GPT-5.3 Chat | Grok 4.5 |
|---|---|---|
| LMArena Vision | — | 1288 |
| Blueprint-Bench 2 | — | 27.3% |
| Furniture Assembly | — | 22.5% |
| LMArena Document | — | 1452 |

## Multilingual

- GPT-5.3 Chat: 50.3 (#124)
- Grok 4.5: 54.4 (#42)

| Benchmark | GPT-5.3 Chat | Grok 4.5 |
|---|---|---|
| LMArena Non-English | 1382 | 1440 |
| LMArena Chinese | 1432 | 1496 |
| LMArena French | 1397 | 1456 |
| LMArena German | 1384 | 1446 |
| LMArena Japanese | 1352 | 1428 |
| LMArena Korean | 1346 | 1404 |
| LMArena Russian | 1400 | 1448 |
| LMArena Spanish | 1371 | 1450 |

## Instruction Following

- GPT-5.3 Chat: 72.8 (#129)
- Grok 4.5: 76.0 (#48)

| Benchmark | GPT-5.3 Chat | Grok 4.5 |
|---|---|---|
| LMArena Instruction Following | 1378 | 1446 |

## Long Context

- GPT-5.3 Chat: 42.6 (#120)
- Grok 4.5: 44.8 (#56)

| Benchmark | GPT-5.3 Chat | Grok 4.5 |
|---|---|---|
| LMArena Longer Query | 1396 | 1463 |

## Writing & Preference

- GPT-5.3 Chat: 63.1 (#68)
- Grok 4.5: 65.8 (#42)

| Benchmark | GPT-5.3 Chat | Grok 4.5 |
|---|---|---|
| LMArena Text | 1389 | 1448 |
| LMArena Creative Writing | 1355 | 1442 |
| EQ-Bench Creative Writing | 1690 | 1579 |
| LMArena Multi-Turn | 1412 | 1456 |

## FAQ

### Is GPT-5.3 Chat better than Grok 4.5?

Grok 4.5 is the stronger model overall, scoring 55.0 to 42.8 on the Noometry Index.

### Which is cheaper, GPT-5.3 Chat or Grok 4.5?

Grok 4.5 is cheaper. It lists at $2 per million input tokens and $6 per million output tokens; GPT-5.3 Chat lists at $1.75 and $14.

### Is GPT-5.3 Chat or Grok 4.5 better for coding?

Grok 4.5 scores higher on coding benchmarks: 52.2 versus 41.4 in the Noometry coding category.

### Which has the bigger context window?

Grok 4.5 does, with 500K tokens against 128K.

### How many benchmarks do GPT-5.3 Chat and Grok 4.5 share?

18 benchmarks have published results for both models. GPT-5.3 Chat has 18 scored results on Noometry and Grok 4.5 has 52.