# GPT-5.1-Codex vs Muse Spark 1.1

> Muse Spark 1.1 is the stronger model overall, scoring 49.9 to 38.2 on the Noometry Index.

- Canonical page: https://noometry.com/compare/gpt-5-1-codex-vs-muse-spark-1-1
- Last updated: 2026-10-10
- Shared benchmarks: 2

## Summary

- They share 2 benchmarks with published results for both. GPT-5.1-Codex scores higher in 1 category and Muse Spark 1.1 in 2 categories; 3 gaps are clear of the uncertainty.
- The widest gap is in math, where Muse Spark 1.1 leads 44.0 to 29.3.
- The biggest single-benchmark swing is ProofBench: 9% for GPT-5.1-Codex and 39% for Muse Spark 1.1.
- Muse Spark 1.1 is cheaper at $1.25 / $4.25 per million input/output tokens, against $1.25 / $10 for GPT-5.1-Codex.
- Muse Spark 1.1 accepts more context: 1.05M tokens versus 400K.

## Snapshot

| | GPT-5.1-Codex | Muse Spark 1.1 |
|---|---|---|
| Provider | OpenAI | Meta |
| Noometry Index | 38.2 | 49.9 |
| Rank | 178 | 43 |
| Context | 400K | 1.05M |
| Input $/M | $1.25 | $1.25 |
| Output $/M | $10 | $4.25 |
| Weights | Proprietary | Proprietary |

## Coding

- GPT-5.1-Codex: 41.7 (#107)
- Muse Spark 1.1: 50.8 (#38)

| Benchmark | GPT-5.1-Codex | Muse Spark 1.1 |
|---|---|---|
| LMArena WebDev | 1337 | 1542 |
| DeepSWE | — | 53.3% |
| SWE-bench Verified (bash only) | 66% | — |
| SciCode | — | 58.8% |
| LMArena Coding | — | 1497 |
| ALE-Bench | 1,245 | — |

## Agentic & Tool Use

- GPT-5.1-Codex: 37.8 (#32)
- Muse Spark 1.1: 33.9 (#45)

| Benchmark | GPT-5.1-Codex | Muse Spark 1.1 |
|---|---|---|
| Terminal-Bench | 60.4% | — |
| τ²-bench Banking | — | 40.5% |
| GBAEval | — | 7.9% |
| GDP.pdf | — | 15% |
| METR Time Horizons | 70.8% | — |
| Vending-Bench 2 | — | 6,520 |

## Reasoning

- GPT-5.1-Codex: —
- Muse Spark 1.1: 45.9 (#41)

| Benchmark | GPT-5.1-Codex | Muse Spark 1.1 |
|---|---|---|
| NYT Connections (extended) | — | 84.9% |
| CritPt | — | 15.1% |
| LMArena Hard Prompts | — | 1486 |
| DTBench | — | 94.4% |
| LMCA | — | 49.9% |
| Surface Evolver Bench | — | 52.5% |
| Epoch Capabilities Index | — | 154.32 |

## Math

- GPT-5.1-Codex: 29.3 (#218)
- Muse Spark 1.1: 44.0 (#67)

| Benchmark | GPT-5.1-Codex | Muse Spark 1.1 |
|---|---|---|
| ProofBench | 9% | 39% |
| LMArena Math | — | 1477 |

## Knowledge

- GPT-5.1-Codex: —
- Muse Spark 1.1: 52.8 (#55)

| Benchmark | GPT-5.1-Codex | Muse Spark 1.1 |
|---|---|---|
| SimpleQA Verified | — | 57.8% |
| LMArena Expert | — | 1480 |

## Multimodal

- GPT-5.1-Codex: —
- Muse Spark 1.1: 41.9 (#28)

| Benchmark | GPT-5.1-Codex | Muse Spark 1.1 |
|---|---|---|
| LMArena Vision | — | 1292 |
| LMArena Document | — | 1465 |

## Multilingual

- GPT-5.1-Codex: —
- Muse Spark 1.1: 56.8 (#16)

| Benchmark | GPT-5.1-Codex | Muse Spark 1.1 |
|---|---|---|
| LMArena Non-English | — | 1471 |
| LMArena Chinese | — | 1518 |
| LMArena French | — | 1494 |
| LMArena German | — | 1466 |
| LMArena Japanese | — | 1445 |
| LMArena Korean | — | 1459 |
| LMArena Russian | — | 1482 |
| LMArena Spanish | — | 1471 |

## Instruction Following

- GPT-5.1-Codex: —
- Muse Spark 1.1: 76.8 (#36)

| Benchmark | GPT-5.1-Codex | Muse Spark 1.1 |
|---|---|---|
| LMArena Instruction Following | — | 1457 |

## Long Context

- GPT-5.1-Codex: —
- Muse Spark 1.1: 44.8 (#55)

| Benchmark | GPT-5.1-Codex | Muse Spark 1.1 |
|---|---|---|
| LMArena Longer Query | — | 1463 |

## Writing & Preference

- GPT-5.1-Codex: —
- Muse Spark 1.1: 73.6 (#11)

| Benchmark | GPT-5.1-Codex | Muse Spark 1.1 |
|---|---|---|
| LMArena Text | — | 1479 |
| LMArena Creative Writing | — | 1440 |
| EQ-Bench Creative Writing | — | 1927 |
| EQ-Bench 4 | — | 1260 |
| LMArena Multi-Turn | — | 1484 |

## FAQ

### Is GPT-5.1-Codex better than Muse Spark 1.1?

Muse Spark 1.1 is the stronger model overall, scoring 49.9 to 38.2 on the Noometry Index.

### Which is cheaper, GPT-5.1-Codex or Muse Spark 1.1?

Muse Spark 1.1 is cheaper. It lists at $1.25 per million input tokens and $4.25 per million output tokens; GPT-5.1-Codex lists at $1.25 and $10.

### Is GPT-5.1-Codex or Muse Spark 1.1 better for coding?

Muse Spark 1.1 scores higher on coding benchmarks: 50.8 versus 41.7 in the Noometry coding category.

### Which has the bigger context window?

Muse Spark 1.1 does, with 1.05M tokens against 400K.

### How many benchmarks do GPT-5.1-Codex and Muse Spark 1.1 share?

2 benchmarks have published results for both models. GPT-5.1-Codex has 6 scored results on Noometry and Muse Spark 1.1 has 36.