# GPT-5.3 Chat vs Grok 4.1 Fast

> GPT-5.3 Chat is the stronger model overall, scoring 42.8 to 41.4 on the Noometry Index. Grok 4.1 Fast costs 18× less per token, which makes it the better buy when GPT-5.3 Chat's lead doesn't matter for your workload.

- Canonical page: https://noometry.com/compare/gpt-5-3-chat-vs-grok-4-1-fast
- 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 6 categories and Grok 4.1 Fast in 2 categories; 5 gaps are clear of the uncertainty.
- The widest gap is in reasoning, where Grok 4.1 Fast leads 43.4 to 28.5.
- Grok 4.1 Fast is cheaper at $0.20 / $0.50 per million input/output tokens, against $1.75 / $14 for GPT-5.3 Chat.

## Snapshot

| | GPT-5.3 Chat | Grok 4.1 Fast |
|---|---|---|
| Provider | OpenAI | xAI |
| Noometry Index | 42.8 | 41.4 |
| Rank | 109 | 136 |
| Context | 128K | 128K |
| Input $/M | $1.75 | $0.20 |
| Output $/M | $14 | $0.50 |
| Weights | Proprietary | Proprietary |

## Coding

- GPT-5.3 Chat: 41.4 (#124)
- Grok 4.1 Fast: 34.1 (#245)

| Benchmark | GPT-5.3 Chat | Grok 4.1 Fast |
|---|---|---|
| LMArena Coding | 1408 | 1411 |
| LMArena WebDev | — | 1242 |
| ALE-Bench | — | 394.93 |

## Agentic & Tool Use

- GPT-5.3 Chat: —
- Grok 4.1 Fast: 36.3 (#39)

| Benchmark | GPT-5.3 Chat | Grok 4.1 Fast |
|---|---|---|
| Berkeley Function Calling Leaderboard | — | 69.6% |
| τ²-bench Banking | — | 13.1% |
| LMArena Search | — | 1171 |
| Vending-Bench 2 | — | 1,107 |

## Reasoning

- GPT-5.3 Chat: 28.5 (#102)
- Grok 4.1 Fast: 43.4 (#49)

| Benchmark | GPT-5.3 Chat | Grok 4.1 Fast |
|---|---|---|
| LMArena Hard Prompts | 1399 | 1407 |
| SimpleBench | — | 56% |
| NYT Connections (extended) | — | 87.4% |
| DTBench | — | 87.7% |
| ForecastBench | — | 61 |

## Math

- GPT-5.3 Chat: 38.2 (#142)
- Grok 4.1 Fast: 31.9 (#221)

| Benchmark | GPT-5.3 Chat | Grok 4.1 Fast |
|---|---|---|
| LMArena Math | 1389 | 1408 |
| MathArena Final-Answer Competitions | — | 60.9% |
| ProofBench | — | 4% |

## Knowledge

- GPT-5.3 Chat: 38.8 (#140)
- Grok 4.1 Fast: 33.1 (#207)

| Benchmark | GPT-5.3 Chat | Grok 4.1 Fast |
|---|---|---|
| LMArena Expert | 1397 | 1399 |
| Vectara Hallucination Rate | — | 17.8% |

## Multimodal

- GPT-5.3 Chat: —
- Grok 4.1 Fast: 37.0 (#76)

| Benchmark | GPT-5.3 Chat | Grok 4.1 Fast |
|---|---|---|
| LMArena Vision | — | 1201 |

## Multilingual

- GPT-5.3 Chat: 50.3 (#124)
- Grok 4.1 Fast: 51.0 (#114)

| Benchmark | GPT-5.3 Chat | Grok 4.1 Fast |
|---|---|---|
| LMArena Non-English | 1382 | 1391 |
| LMArena Chinese | 1432 | 1441 |
| LMArena French | 1397 | 1415 |
| LMArena German | 1384 | 1404 |
| LMArena Japanese | 1352 | 1349 |
| LMArena Korean | 1346 | 1361 |
| LMArena Russian | 1400 | 1387 |
| LMArena Spanish | 1371 | 1413 |

## Instruction Following

- GPT-5.3 Chat: 72.8 (#129)
- Grok 4.1 Fast: 72.7 (#133)

| Benchmark | GPT-5.3 Chat | Grok 4.1 Fast |
|---|---|---|
| LMArena Instruction Following | 1378 | 1376 |

## Long Context

- GPT-5.3 Chat: 42.6 (#120)
- Grok 4.1 Fast: 42.4 (#126)

| Benchmark | GPT-5.3 Chat | Grok 4.1 Fast |
|---|---|---|
| LMArena Longer Query | 1396 | 1390 |

## Writing & Preference

- GPT-5.3 Chat: 63.1 (#68)
- Grok 4.1 Fast: 57.2 (#131)

| Benchmark | GPT-5.3 Chat | Grok 4.1 Fast |
|---|---|---|
| LMArena Text | 1389 | 1408 |
| LMArena Creative Writing | 1355 | 1394 |
| EQ-Bench Creative Writing | 1690 | 1327 |
| LMArena Multi-Turn | 1412 | 1389 |

## FAQ

### Is GPT-5.3 Chat better than Grok 4.1 Fast?

GPT-5.3 Chat is the stronger model overall, scoring 42.8 to 41.4 on the Noometry Index. Grok 4.1 Fast costs 18× less per token, which makes it the better buy when GPT-5.3 Chat's lead doesn't matter for your workload.

### Which is cheaper, GPT-5.3 Chat or Grok 4.1 Fast?

Grok 4.1 Fast is cheaper. It lists at $0.20 per million input tokens and $0.50 per million output tokens; GPT-5.3 Chat lists at $1.75 and $14.

### Is GPT-5.3 Chat or Grok 4.1 Fast better for coding?

GPT-5.3 Chat scores higher on coding benchmarks: 41.4 versus 34.1 in the Noometry coding category.

### Which has the bigger context window?

Both accept 128K tokens.

### How many benchmarks do GPT-5.3 Chat and Grok 4.1 Fast share?

18 benchmarks have published results for both models. GPT-5.3 Chat has 18 scored results on Noometry and Grok 4.1 Fast has 32.