# GPT-5.5 Instant vs GPT-5-Codex

> GPT-5.5 Instant is the stronger model overall, scoring 42.7 to 37.9 on the Noometry Index.

- Canonical page: https://noometry.com/compare/gpt-5-5-instant-vs-gpt-5-codex
- Last updated: 2026-10-10
- Shared benchmarks: 0

## Summary

- The widest gap is in reasoning, where GPT-5-Codex leads 30.9 to 24.9.

## Snapshot

| | GPT-5.5 Instant | GPT-5-Codex |
|---|---|---|
| Provider | OpenAI | OpenAI |
| Noometry Index | 42.7 | 37.9 |
| Rank | 110 | 192 |
| Context | — | 400K |
| Input $/M | — | $1.25 |
| Output $/M | — | $10 |
| Weights | Proprietary | Proprietary |

## Coding

- GPT-5.5 Instant: 44.3 (#74)
- GPT-5-Codex: 42.4 (#103)

| Benchmark | GPT-5.5 Instant | GPT-5-Codex |
|---|---|---|
| SciCode | 48.6% | — |
| WeirdML | — | 54.5% |
| LMArena Coding | 1433 | — |

## Agentic & Tool Use

- GPT-5.5 Instant: —
- GPT-5-Codex: 31.0 (#72)

| Benchmark | GPT-5.5 Instant | GPT-5-Codex |
|---|---|---|
| Terminal-Bench | — | 44.3% |

## Reasoning

- GPT-5.5 Instant: 24.9 (#155)
- GPT-5-Codex: 30.9 (#83)

| Benchmark | GPT-5.5 Instant | GPT-5-Codex |
|---|---|---|
| Kagi LLM Benchmark | — | 70.3% |
| CritPt | 0% | — |
| Chess Puzzles | 12% | — |
| LMArena Hard Prompts | 1426 | — |
| Epoch Capabilities Index | 142.52 | — |

## Math

- GPT-5.5 Instant: 26.5 (#259)
- GPT-5-Codex: —

| Benchmark | GPT-5.5 Instant | GPT-5-Codex |
|---|---|---|
| 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 (#74)
- GPT-5-Codex: —

| Benchmark | GPT-5.5 Instant | GPT-5-Codex |
|---|---|---|
| GPQA Diamond | 82.5% | — |
| LMArena Expert | 1409 | — |

## Multimodal

- GPT-5.5 Instant: 40.0 (#52)
- GPT-5-Codex: —

| Benchmark | GPT-5.5 Instant | GPT-5-Codex |
|---|---|---|
| LMArena Vision | 1250 | — |
| LMArena Document | 1403 | — |

## Multilingual

- GPT-5.5 Instant: 52.8 (#80)
- GPT-5-Codex: —

| Benchmark | GPT-5.5 Instant | GPT-5-Codex |
|---|---|---|
| LMArena Non-English | 1417 | — |
| LMArena Chinese | 1456 | — |
| LMArena French | 1428 | — |
| LMArena German | 1411 | — |
| LMArena Japanese | 1408 | — |
| LMArena Korean | 1392 | — |
| LMArena Russian | 1431 | — |
| LMArena Spanish | 1429 | — |

## Instruction Following

- GPT-5.5 Instant: 74.2 (#100)
- GPT-5-Codex: —

| Benchmark | GPT-5.5 Instant | GPT-5-Codex |
|---|---|---|
| LMArena Instruction Following | 1406 | — |

## Long Context

- GPT-5.5 Instant: 43.4 (#96)
- GPT-5-Codex: —

| Benchmark | GPT-5.5 Instant | GPT-5-Codex |
|---|---|---|
| LMArena Longer Query | 1422 | — |

## Writing & Preference

- GPT-5.5 Instant: 61.8 (#85)
- GPT-5-Codex: —

| Benchmark | GPT-5.5 Instant | GPT-5-Codex |
|---|---|---|
| LMArena Text | 1419 | — |
| LMArena Creative Writing | 1419 | — |
| LMArena Multi-Turn | 1433 | — |

## FAQ

### Is GPT-5.5 Instant better than GPT-5-Codex?

GPT-5.5 Instant is the stronger model overall, scoring 42.7 to 37.9 on the Noometry Index.

### Is GPT-5.5 Instant or GPT-5-Codex better for coding?

GPT-5.5 Instant scores higher on coding benchmarks: 44.3 versus 42.4 in the Noometry coding category.

### How many benchmarks do GPT-5.5 Instant and GPT-5-Codex share?

0 benchmarks have published results for both models. GPT-5.5 Instant has 27 scored results on Noometry and GPT-5-Codex has 3.