# GPT-4.5 vs GPT-5.5 Instant

> GPT-5.5 Instant is the stronger model overall, scoring 42.7 to 37.2 on the Noometry Index.

- Canonical page: https://noometry.com/compare/gpt-4-5-vs-gpt-5-5-instant
- Last updated: 2026-10-12
- Shared benchmarks: 20

## Summary

- They share 20 benchmarks with published results for both. GPT-4.5 scores higher in 1 category and GPT-5.5 Instant in 8 categories; 8 gaps are clear of the uncertainty.
- The widest gap is in knowledge, where GPT-5.5 Instant leads 48.9 to 32.5.
- The biggest single-benchmark swing is OTIS Mock AIME 2024-2025: 37.8% for GPT-4.5 and 68.1% for GPT-5.5 Instant.

## Snapshot

| | GPT-4.5 | GPT-5.5 Instant |
|---|---|---|
| Provider | OpenAI | OpenAI |
| Noometry Index | 37.2 | 42.7 |
| Rank | 208 | 110 |
| Context | — | — |
| Input $/M | — | — |
| Output $/M | — | — |
| Weights | Proprietary | Proprietary |

## Coding

- GPT-4.5: 42.2 (#109)
- GPT-5.5 Instant: 44.3 (#74)

| Benchmark | GPT-4.5 | GPT-5.5 Instant |
|---|---|---|
| LMArena Coding | 1396 | 1433 |
| Aider Polyglot | 44.9% | — |
| SciCode | — | 48.6% |
| WeirdML | 39.4% | — |
| LiveBench Coding | 75.2% | — |

## Agentic & Tool Use

- GPT-4.5: 27.9 (#97)
- GPT-5.5 Instant: —

| Benchmark | GPT-4.5 | GPT-5.5 Instant |
|---|---|---|
| Cybench | 17.5% | — |

## Reasoning

- GPT-4.5: 13.9 (#330)
- GPT-5.5 Instant: 24.9 (#155)

| Benchmark | GPT-4.5 | GPT-5.5 Instant |
|---|---|---|
| LMArena Hard Prompts | 1403 | 1426 |
| Epoch Capabilities Index | 136.74 | 142.52 |
| ARC-AGI-2 | 0.8% | — |
| SimpleBench | 34.5% | — |
| ARC-AGI-1 | 10.3% | — |
| CritPt | — | 0% |
| Chess Puzzles | — | 12% |
| EnigmaEval | 3.2% | — |
| LiveBench Reasoning | 71.1% | — |
| LiveBench Data Analysis | 64.3% | — |
| ForecastBench | 61.7 | — |
| LiveBench | 69% | — |

## Math

- GPT-4.5: 32.6 (#211)
- GPT-5.5 Instant: 26.5 (#259)

| Benchmark | GPT-4.5 | GPT-5.5 Instant |
|---|---|---|
| OTIS Mock AIME 2024-2025 | 37.8% | 68.1% |
| LMArena Math | 1412 | 1420 |
| FrontierMath (Tiers 1-3) | — | 26.3% |
| FrontierMath Tier 4 | — | 2.4% |
| LiveBench Math | 69.3% | — |
| MATH Level 5 | 78.6% | — |

## Knowledge

- GPT-4.5: 32.5 (#211)
- GPT-5.5 Instant: 48.9 (#74)

| Benchmark | GPT-4.5 | GPT-5.5 Instant |
|---|---|---|
| GPQA Diamond | 68.7% | 82.5% |
| LMArena Expert | 1394 | 1409 |
| Humanity's Last Exam | 5.4% | — |
| Confabulations | 13.6% | — |

## Multimodal

- GPT-4.5: 37.6 (#71)
- GPT-5.5 Instant: 40.0 (#52)

| Benchmark | GPT-4.5 | GPT-5.5 Instant |
|---|---|---|
| LMArena Vision | 1195 | 1250 |
| VPCT | 45% | — |
| LMArena Document | — | 1403 |

## Multilingual

- GPT-4.5: 52.5 (#83)
- GPT-5.5 Instant: 52.8 (#80)

| Benchmark | GPT-4.5 | GPT-5.5 Instant |
|---|---|---|
| LMArena Non-English | 1413 | 1417 |
| LMArena Chinese | 1421 | 1456 |
| LMArena French | 1418 | 1428 |
| LMArena German | 1457 | 1411 |
| LMArena Japanese | 1416 | 1408 |
| LMArena Korean | 1392 | 1392 |
| LMArena Russian | 1419 | 1431 |
| LMArena Spanish | — | 1429 |

## Instruction Following

- GPT-4.5: 72.6 (#134)
- GPT-5.5 Instant: 74.2 (#100)

| Benchmark | GPT-4.5 | GPT-5.5 Instant |
|---|---|---|
| LMArena Instruction Following | 1404 | 1406 |
| LiveBench Instruction Following | 72.3% | — |

## Long Context

- GPT-4.5: 40.4 (#155)
- GPT-5.5 Instant: 43.4 (#96)

| Benchmark | GPT-4.5 | GPT-5.5 Instant |
|---|---|---|
| LMArena Longer Query | 1406 | 1422 |
| Fiction.LiveBench | 63.9% | — |

## Writing & Preference

- GPT-4.5: 56.9 (#134)
- GPT-5.5 Instant: 61.8 (#85)

| Benchmark | GPT-4.5 | GPT-5.5 Instant |
|---|---|---|
| LMArena Text | 1417 | 1419 |
| LMArena Creative Writing | 1394 | 1419 |
| LMArena Multi-Turn | 1444 | 1433 |
| Short-Story Creative Writing | 75.6% | — |
| EQ-Bench Creative Writing | 1258 | — |
| LiveBench Language | 61.5% | — |

## FAQ

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

GPT-5.5 Instant is the stronger model overall, scoring 42.7 to 37.2 on the Noometry Index.

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

GPT-5.5 Instant scores higher on coding benchmarks: 44.3 versus 42.2 in the Noometry coding category.

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

20 benchmarks have published results for both models. GPT-4.5 has 42 scored results on Noometry and GPT-5.5 Instant has 27.