# GPT-5.1-Codex vs Muse Glimmer

> Muse Glimmer is the stronger model overall, scoring 41.3 to 38.2 on the Noometry Index.

- Canonical page: https://noometry.com/compare/gpt-5-1-codex-vs-muse-glimmer
- Last updated: 2026-10-10
- Shared benchmarks: 1

## Summary

- They share 1 benchmark with published results for both. GPT-5.1-Codex scores higher in 1 category and Muse Glimmer in 1 category; 2 gaps are clear of the uncertainty.
- The widest gap is in math, where Muse Glimmer leads 36.1 to 29.3.
- Muse Glimmer has downloadable open weights; the other is API-only.

## Snapshot

| | GPT-5.1-Codex | Muse Glimmer |
|---|---|---|
| Provider | OpenAI | Meta |
| Noometry Index | 38.2 | 41.3 |
| Rank | 178 | 128 |
| Context | 400K | — |
| Input $/M | $1.25 | — |
| Output $/M | $10 | — |
| Weights | Proprietary | Open |

## Coding

- GPT-5.1-Codex: 41.7 (#107)
- Muse Glimmer: 38.7 (#157)

| Benchmark | GPT-5.1-Codex | Muse Glimmer |
|---|---|---|
| LMArena WebDev | 1337 | 1355 |
| SWE-bench Verified (bash only) | 66% | — |
| LMArena Coding | — | 1417 |
| ALE-Bench | 1,245 | — |

## Agentic & Tool Use

- GPT-5.1-Codex: 37.8 (#32)
- Muse Glimmer: —

| Benchmark | GPT-5.1-Codex | Muse Glimmer |
|---|---|---|
| Terminal-Bench | 60.4% | — |
| METR Time Horizons | 70.8% | — |

## Reasoning

- GPT-5.1-Codex: —
- Muse Glimmer: 27.2 (#111)

| Benchmark | GPT-5.1-Codex | Muse Glimmer |
|---|---|---|
| LMArena Hard Prompts | — | 1395 |

## Math

- GPT-5.1-Codex: 29.3 (#218)
- Muse Glimmer: 36.1 (#128)

| Benchmark | GPT-5.1-Codex | Muse Glimmer |
|---|---|---|
| ProofBench | 9% | — |
| LMArena Math | — | 1419 |

## Knowledge

- GPT-5.1-Codex: —
- Muse Glimmer: 37.9 (#140)

| Benchmark | GPT-5.1-Codex | Muse Glimmer |
|---|---|---|
| LMArena Expert | — | 1388 |

## Multilingual

- GPT-5.1-Codex: —
- Muse Glimmer: 50.6 (#117)

| Benchmark | GPT-5.1-Codex | Muse Glimmer |
|---|---|---|
| LMArena Non-English | — | 1384 |
| LMArena Chinese | — | 1412 |
| LMArena Russian | — | 1393 |

## Instruction Following

- GPT-5.1-Codex: —
- Muse Glimmer: 72.7 (#134)

| Benchmark | GPT-5.1-Codex | Muse Glimmer |
|---|---|---|
| LMArena Instruction Following | — | 1374 |

## Long Context

- GPT-5.1-Codex: —
- Muse Glimmer: 42.1 (#124)

| Benchmark | GPT-5.1-Codex | Muse Glimmer |
|---|---|---|
| LMArena Longer Query | — | 1381 |

## Writing & Preference

- GPT-5.1-Codex: —
- Muse Glimmer: 57.7 (#122)

| Benchmark | GPT-5.1-Codex | Muse Glimmer |
|---|---|---|
| LMArena Text | — | 1389 |
| LMArena Creative Writing | — | 1338 |
| LMArena Multi-Turn | — | 1398 |

## FAQ

### Is GPT-5.1-Codex better than Muse Glimmer?

Muse Glimmer is the stronger model overall, scoring 41.3 to 38.2 on the Noometry Index.

### Is GPT-5.1-Codex or Muse Glimmer better for coding?

GPT-5.1-Codex scores higher on coding benchmarks: 41.7 versus 38.7 in the Noometry coding category.

### How many benchmarks do GPT-5.1-Codex and Muse Glimmer share?

1 benchmark has published results for both models. GPT-5.1-Codex has 6 scored results on Noometry and Muse Glimmer has 13.