# GPT-5 Nano vs Grok 4.5

> Grok 4.5 is the stronger model overall, scoring 55.0 to 33.5 on the Noometry Index. GPT-5 Nano costs 22× less per token, which makes it the better buy when Grok 4.5's lead doesn't matter for your workload.

- Canonical page: https://noometry.com/compare/gpt-5-nano-vs-grok-4-5
- Last updated: 2026-10-12
- Shared benchmarks: 33

## Summary

- They share 33 benchmarks with published results for both. GPT-5 Nano scores higher in 0 categories and Grok 4.5 in 10 categories; 10 gaps are clear of the uncertainty.
- The widest gap is in reasoning, where Grok 4.5 leads 56.1 to 16.3.
- The biggest single-benchmark swing is ARC-AGI-1: 20.7% for GPT-5 Nano and 87.2% for Grok 4.5.
- GPT-5 Nano is cheaper at $0.05 / $0.40 per million input/output tokens, against $2 / $6 for Grok 4.5.
- Grok 4.5 accepts more context: 500K tokens versus 400K.

## Snapshot

| | GPT-5 Nano | Grok 4.5 |
|---|---|---|
| Provider | OpenAI | xAI |
| Noometry Index | 33.5 | 55.0 |
| Rank | 241 | 25 |
| Context | 400K | 500K |
| Input $/M | $0.05 | $2 |
| Output $/M | $0.40 | $6 |
| Weights | Proprietary | Proprietary |

## Coding

- GPT-5 Nano: 33.6 (#254)
- Grok 4.5: 52.2 (#35)

| Benchmark | GPT-5 Nano | Grok 4.5 |
|---|---|---|
| WeirdML | 38.1% | 46.4% |
| LMArena Coding | 1351 | 1474 |
| ALE-Bench | 718.67 | 1,309 |
| DeepSWE | — | 53.8% |
| FrontierCode | — | 42.4% |
| SWE-bench Verified (bash only) | 34.8% | — |
| LMArena WebDev | — | 1553 |
| SciCode | — | 54.1% |

## Agentic & Tool Use

- GPT-5 Nano: 25.8 (#106)
- Grok 4.5: 44.4 (#17)

| Benchmark | GPT-5 Nano | Grok 4.5 |
|---|---|---|
| Terminal-Bench | 21.8% | — |
| APEX-Agents | — | 56.2% |
| Berkeley Function Calling Leaderboard | 51.5% | — |
| 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 Nano: 16.3 (#306)
- Grok 4.5: 56.1 (#25)

| Benchmark | GPT-5 Nano | Grok 4.5 |
|---|---|---|
| ARC-AGI-2 | 2.6% | 52.6% |
| Kagi LLM Benchmark | 62.2% | 83.5% |
| ARC-AGI-1 | 20.7% | 87.2% |
| Chess Puzzles | 27% | 36% |
| LMArena Hard Prompts | 1328 | 1462 |
| DTBench | 62.7% | 96.5% |
| LMCA | 7.9% | 45.2% |
| Epoch Capabilities Index | 139.38 | 153.92 |
| SimpleBench | — | 70% |
| NYT Connections (extended) | — | 79.9% |
| CritPt | — | 15.4% |
| Mystery Game Puzzles | 9% | — |
| Surface Evolver Bench | — | 74.4% |
| ForecastBench | 59.1 | — |

## Math

- GPT-5 Nano: 29.4 (#241)
- Grok 4.5: 60.9 (#35)

| Benchmark | GPT-5 Nano | Grok 4.5 |
|---|---|---|
| FrontierMath (Tiers 1-3) | 20% | 57.2% |
| FrontierMath Tier 4 | 2.4% | 24.4% |
| OTIS Mock AIME 2024-2025 | 81.1% | 97.8% |
| ProofBench | 12% | 31% |
| LMArena Math | 1317 | 1459 |
| Omni-MATH | 54.6% | — |
| MATH Level 5 | 95.2% | — |
| FrontierMath (Feb 2025 set) | 8.3% | — |
| FrontierMath Tier 4 (v1) | 2.1% | — |

## Knowledge

- GPT-5 Nano: 35.9 (#178)
- Grok 4.5: 62.3 (#24)

| Benchmark | GPT-5 Nano | Grok 4.5 |
|---|---|---|
| GPQA Diamond | 69.4% | 93.4% |
| SimpleQA Verified | 11.7% | 48.3% |
| LMArena Expert | 1321 | 1466 |
| MMLU-Pro | 77.8% | — |
| Vectara Hallucination Rate | 10.5% | — |
| GPQA (HELM) | 67.9% | — |

## Multimodal

- GPT-5 Nano: 31.3 (#108)
- Grok 4.5: 37.6 (#72)

| Benchmark | GPT-5 Nano | Grok 4.5 |
|---|---|---|
| LMArena Vision | 1159 | 1288 |
| VPCT | 37.2% | — |
| Blueprint-Bench 2 | — | 27.3% |
| Furniture Assembly | — | 22.5% |
| LMArena Document | — | 1452 |

## Multilingual

- GPT-5 Nano: 45.3 (#172)
- Grok 4.5: 54.4 (#42)

| Benchmark | GPT-5 Nano | Grok 4.5 |
|---|---|---|
| LMArena Non-English | 1313 | 1440 |
| LMArena Chinese | 1356 | 1496 |
| LMArena German | 1327 | 1446 |
| LMArena Japanese | 1226 | 1428 |
| LMArena Korean | 1269 | 1404 |
| LMArena Russian | 1296 | 1448 |
| LMArena Spanish | 1360 | 1450 |
| LMArena French | — | 1456 |

## Instruction Following

- GPT-5 Nano: 75.0 (#79)
- Grok 4.5: 76.0 (#48)

| Benchmark | GPT-5 Nano | Grok 4.5 |
|---|---|---|
| LMArena Instruction Following | 1306 | 1446 |
| IFEval | 93.2% | — |

## Long Context

- GPT-5 Nano: 31.3 (#281)
- Grok 4.5: 44.8 (#56)

| Benchmark | GPT-5 Nano | Grok 4.5 |
|---|---|---|
| LMArena Longer Query | 1312 | 1463 |
| Fiction.LiveBench | 44.4% | — |

## Writing & Preference

- GPT-5 Nano: 39.1 (#249)
- Grok 4.5: 65.8 (#42)

| Benchmark | GPT-5 Nano | Grok 4.5 |
|---|---|---|
| LMArena Text | 1320 | 1448 |
| LMArena Creative Writing | 1249 | 1442 |
| EQ-Bench Creative Writing | 705 | 1579 |
| LMArena Multi-Turn | 1311 | 1456 |
| WildBench | 80.6% | — |

## FAQ

### Is GPT-5 Nano better than Grok 4.5?

Grok 4.5 is the stronger model overall, scoring 55.0 to 33.5 on the Noometry Index. GPT-5 Nano costs 22× less per token, which makes it the better buy when Grok 4.5's lead doesn't matter for your workload.

### Which is cheaper, GPT-5 Nano or Grok 4.5?

GPT-5 Nano is cheaper. It lists at $0.05 per million input tokens and $0.40 per million output tokens; Grok 4.5 lists at $2 and $6.

### Is GPT-5 Nano or Grok 4.5 better for coding?

Grok 4.5 scores higher on coding benchmarks: 52.2 versus 33.6 in the Noometry coding category.

### Which has the bigger context window?

Grok 4.5 does, with 500K tokens against 400K.

### How many benchmarks do GPT-5 Nano and Grok 4.5 share?

33 benchmarks have published results for both models. GPT-5 Nano has 49 scored results on Noometry and Grok 4.5 has 52.