# GPT-5.5 vs Grok 4.5

> GPT-5.5 is the stronger model overall, scoring 63.4 to 55.0 on the Noometry Index. Grok 4.5 costs 3.8× less per token, which makes it the better buy when GPT-5.5's lead doesn't matter for your workload.

- Canonical page: https://noometry.com/compare/gpt-5-5-vs-grok-4-5
- Last updated: 2026-10-10
- Shared benchmarks: 52

## Summary

- They share 52 benchmarks with published results for both. GPT-5.5 scores higher in 10 categories and Grok 4.5 in 0 categories; 10 gaps are clear of the uncertainty.
- The widest gap is in math, where GPT-5.5 leads 81.5 to 60.7.
- The biggest single-benchmark swing is FrontierMath Tier 4: 72.5% for GPT-5.5 and 24.4% for Grok 4.5.
- Grok 4.5 is cheaper at $2 / $6 per million input/output tokens, against $5 / $30 for GPT-5.5.
- GPT-5.5 accepts more context: 1.05M tokens versus 500K.

## Snapshot

| | GPT-5.5 | Grok 4.5 |
|---|---|---|
| Provider | OpenAI | xAI |
| Noometry Index | 63.4 | 55.0 |
| Rank | 8 | 22 |
| Context | 1.05M | 500K |
| Input $/M | $5 | $2 |
| Output $/M | $30 | $6 |
| Weights | Proprietary | Proprietary |

## Coding

- GPT-5.5: 58.3 (#13)
- Grok 4.5: 51.7 (#34)

| Benchmark | GPT-5.5 | Grok 4.5 |
|---|---|---|
| DeepSWE | 67% | 53.8% |
| FrontierCode | 43% | 42.4% |
| LMArena WebDev | 1512 | 1552 |
| SciCode | 56.1% | 54.1% |
| WeirdML | 84.9% | 46.4% |
| LMArena Coding | 1494 | 1473 |
| ALE-Bench | 1,943 | 1,309 |
| SWE-bench Verified | 80.6% | — |
| GSO | 40.2% | — |
| MirrorCode | 10% | — |

## Agentic & Tool Use

- GPT-5.5: 50.7 (#6)
- Grok 4.5: 44.4 (#15)

| Benchmark | GPT-5.5 | Grok 4.5 |
|---|---|---|
| APEX-Agents | 55.1% | 56.2% |
| τ²-bench Banking | 44.6% | 47.9% |
| PostTrainBench | 27.2% | 23.4% |
| GBAEval | 53.2% | 65.4% |
| GDP.pdf | 26% | 14% |
| LMArena Search | 1242 | 1213 |
| Vending-Bench 2 | 7,524 | 3,887 |
| Terminal-Bench | 84.7% | — |
| OSWorld 2.0 | 13% | — |
| Remote Labor Index | 6.3% | — |
| DeepResearch Bench | 54% | — |
| ExploitBench | 47.4% | — |

## Reasoning

- GPT-5.5: 72.7 (#8)
- Grok 4.5: 56.0 (#23)

| Benchmark | GPT-5.5 | Grok 4.5 |
|---|---|---|
| ARC-AGI-2 | 85% | 52.6% |
| SimpleBench | 69% | 70% |
| Kagi LLM Benchmark | 88.8% | 83.5% |
| NYT Connections (extended) | 96.2% | 79.9% |
| ARC-AGI-1 | 95% | 87.2% |
| CritPt | 27.1% | 15.4% |
| Chess Puzzles | 54% | 36% |
| LMArena Hard Prompts | 1489 | 1462 |
| DTBench | 96% | 96.5% |
| LMCA | 54.3% | 45.2% |
| Surface Evolver Bench | 88.1% | 74.4% |
| Epoch Capabilities Index | 159.25 | 154.02 |
| EBR-Bench | 34.3% | — |
| Mystery Game Puzzles | 56% | — |
| Bench to the Future 3 | 0.14 | — |
| ForecastBench | 60.6 | — |

## Math

- GPT-5.5: 81.5 (#9)
- Grok 4.5: 60.7 (#29)

| Benchmark | GPT-5.5 | Grok 4.5 |
|---|---|---|
| FrontierMath (Tiers 1-3) | 85.3% | 57.2% |
| FrontierMath Tier 4 | 72.5% | 24.4% |
| OTIS Mock AIME 2024-2025 | 100% | 97.8% |
| ProofBench | 50% | 31% |
| LMArena Math | 1486 | 1457 |
| MathArena Final-Answer Competitions | 94.3% | — |
| FrontierMath (Feb 2025 set) | 51.7% | — |
| FrontierMath Erdős | 0% | — |
| FrontierMath Tier 4 (v1) | 35.4% | — |

## Knowledge

- GPT-5.5: 64.4 (#14)
- Grok 4.5: 62.3 (#21)

| Benchmark | GPT-5.5 | Grok 4.5 |
|---|---|---|
| GPQA Diamond | 94% | 93.4% |
| SimpleQA Verified | 63% | 48.3% |
| LMArena Expert | 1508 | 1466 |
| Vectara Hallucination Rate | 9.3% | — |

## Multimodal

- GPT-5.5: 47.1 (#11)
- Grok 4.5: 37.8 (#63)

| Benchmark | GPT-5.5 | Grok 4.5 |
|---|---|---|
| LMArena Vision | 1297 | 1287 |
| Blueprint-Bench 2 | 36.2% | 27.3% |
| Furniture Assembly | 44.2% | 22.5% |
| LMArena Document | 1486 | 1452 |

## Multilingual

- GPT-5.5: 56.5 (#19)
- Grok 4.5: 54.5 (#43)

| Benchmark | GPT-5.5 | Grok 4.5 |
|---|---|---|
| LMArena Non-English | 1467 | 1439 |
| LMArena Chinese | 1535 | 1497 |
| LMArena French | 1486 | 1458 |
| LMArena German | 1478 | 1448 |
| LMArena Japanese | 1498 | 1425 |
| LMArena Korean | 1461 | 1402 |
| LMArena Russian | 1473 | 1447 |
| LMArena Spanish | 1469 | 1452 |

## Instruction Following

- GPT-5.5: 77.7 (#18)
- Grok 4.5: 76.3 (#45)

| Benchmark | GPT-5.5 | Grok 4.5 |
|---|---|---|
| LMArena Instruction Following | 1479 | 1446 |

## Long Context

- GPT-5.5: 48.3 (#12)
- Grok 4.5: 44.8 (#54)

| Benchmark | GPT-5.5 | Grok 4.5 |
|---|---|---|
| LMArena Longer Query | 1484 | 1463 |
| CL-bench Life | 22.2% | — |

## Writing & Preference

- GPT-5.5: 72.8 (#13)
- Grok 4.5: 65.9 (#40)

| Benchmark | GPT-5.5 | Grok 4.5 |
|---|---|---|
| LMArena Text | 1471 | 1448 |
| LMArena Creative Writing | 1455 | 1442 |
| EQ-Bench Creative Writing | 1844 | 1579 |
| LMArena Multi-Turn | 1477 | 1457 |
| EQ-Bench 4 | 1315 | — |

## FAQ

### Is GPT-5.5 better than Grok 4.5?

GPT-5.5 is the stronger model overall, scoring 63.4 to 55.0 on the Noometry Index. Grok 4.5 costs 3.8× less per token, which makes it the better buy when GPT-5.5's lead doesn't matter for your workload.

### Which is cheaper, GPT-5.5 or Grok 4.5?

Grok 4.5 is cheaper. It lists at $2 per million input tokens and $6 per million output tokens; GPT-5.5 lists at $5 and $30.

### Is GPT-5.5 or Grok 4.5 better for coding?

GPT-5.5 scores higher on coding benchmarks: 58.3 versus 51.7 in the Noometry coding category.

### Which has the bigger context window?

GPT-5.5 does, with 1.05M tokens against 500K.

### How many benchmarks do GPT-5.5 and Grok 4.5 share?

52 benchmarks have published results for both models. GPT-5.5 has 71 scored results on Noometry and Grok 4.5 has 52.