# GPT-5.5 Instant vs Mercury 2

> GPT-5.5 Instant is the stronger model overall, scoring 42.5 to 38.8 on the Noometry Index.

- Canonical page: https://noometry.com/compare/gpt-5-5-instant-vs-mercury-2
- Last updated: 2026-10-10
- Shared benchmarks: 13

## Summary

- They share 13 benchmarks with published results for both. GPT-5.5 Instant scores higher in 7 categories and Mercury 2 in 0 categories; 7 gaps are clear of the uncertainty.
- The widest gap is in knowledge, where GPT-5.5 Instant leads 48.9 to 35.6.
- The biggest single-benchmark swing is SciCode: 48.6% for GPT-5.5 Instant and 38.7% for Mercury 2.

## Snapshot

| | GPT-5.5 Instant | Mercury 2 |
|---|---|---|
| Provider | OpenAI | Inception |
| Noometry Index | 42.5 | 38.8 |
| Rank | 99 | 167 |
| Context | — | 128K |
| Input $/M | — | $0.25 |
| Output $/M | — | $0.75 |
| Weights | Proprietary | Proprietary |

## Coding

- GPT-5.5 Instant: 43.7 (#73)
- Mercury 2: 33.2 (#250)

| Benchmark | GPT-5.5 Instant | Mercury 2 |
|---|---|---|
| SciCode | 48.6% | 38.7% |
| LMArena Coding | 1433 | 1391 |
| LMArena WebDev | — | 1170 |
| WeirdML | — | 43.2% |
| ALE-Bench | — | 785.58 |

## Reasoning

- GPT-5.5 Instant: 24.2 (#149)
- Mercury 2: 23.0 (#170)

| Benchmark | GPT-5.5 Instant | Mercury 2 |
|---|---|---|
| CritPt | 0% | 0.8% |
| LMArena Hard Prompts | 1426 | 1362 |
| Chess Puzzles | 12% | — |
| Epoch Capabilities Index | 142.48 | — |

## Math

- GPT-5.5 Instant: 26.1 (#241)
- Mercury 2: —

| Benchmark | GPT-5.5 Instant | Mercury 2 |
|---|---|---|
| FrontierMath (Tiers 1-3) | 26.3% | — |
| FrontierMath Tier 4 | 2.4% | — |
| OTIS Mock AIME 2024-2025 | 68.1% | — |
| LMArena Math | 1420 | — |

## Knowledge

- GPT-5.5 Instant: 48.9 (#68)
- Mercury 2: 35.6 (#170)

| Benchmark | GPT-5.5 Instant | Mercury 2 |
|---|---|---|
| LMArena Expert | 1409 | 1358 |
| GPQA Diamond | 82.5% | — |
| Vectara Hallucination Rate | — | 12.3% |

## Multimodal

- GPT-5.5 Instant: 39.3 (#48)
- Mercury 2: —

| Benchmark | GPT-5.5 Instant | Mercury 2 |
|---|---|---|
| LMArena Vision | 1250 | — |
| LMArena Document | 1403 | — |

## Multilingual

- GPT-5.5 Instant: 53.0 (#76)
- Mercury 2: 46.8 (#153)

| Benchmark | GPT-5.5 Instant | Mercury 2 |
|---|---|---|
| LMArena Non-English | 1417 | 1331 |
| LMArena Chinese | 1457 | 1416 |
| LMArena Russian | 1430 | 1303 |
| LMArena French | 1428 | — |
| LMArena German | 1410 | — |
| LMArena Japanese | 1408 | — |
| LMArena Korean | 1393 | — |
| LMArena Spanish | 1430 | — |

## Instruction Following

- GPT-5.5 Instant: 74.4 (#94)
- Mercury 2: 70.4 (#161)

| Benchmark | GPT-5.5 Instant | Mercury 2 |
|---|---|---|
| LMArena Instruction Following | 1407 | 1328 |

## Long Context

- GPT-5.5 Instant: 43.4 (#92)
- Mercury 2: 40.4 (#149)

| Benchmark | GPT-5.5 Instant | Mercury 2 |
|---|---|---|
| LMArena Longer Query | 1422 | 1329 |

## Writing & Preference

- GPT-5.5 Instant: 62.0 (#81)
- Mercury 2: 54.0 (#151)

| Benchmark | GPT-5.5 Instant | Mercury 2 |
|---|---|---|
| LMArena Text | 1419 | 1355 |
| LMArena Creative Writing | 1420 | 1289 |
| LMArena Multi-Turn | 1434 | 1358 |

## FAQ

### Is GPT-5.5 Instant better than Mercury 2?

GPT-5.5 Instant is the stronger model overall, scoring 42.5 to 38.8 on the Noometry Index.

### Is GPT-5.5 Instant or Mercury 2 better for coding?

GPT-5.5 Instant scores higher on coding benchmarks: 43.7 versus 33.2 in the Noometry coding category.

### How many benchmarks do GPT-5.5 Instant and Mercury 2 share?

13 benchmarks have published results for both models. GPT-5.5 Instant has 27 scored results on Noometry and Mercury 2 has 17.