Noometry

Model comparison

GPT-5.1-Codex vs Muse Spark 1.2

Muse Spark 1.2 is the stronger model overall, scoring 49.8 to 38.2 on the Noometry Index.

Last verified . 2 shared benchmarks.

GPT-5.1-Codex OpenAI

38.2

Rank #178 Reported

Muse Spark 1.2 Meta

49.8

Rank #44 Confirmed

Summary

  • They share 2 benchmarks with published results for both. GPT-5.1-Codex scores higher in 1 category and Muse Spark 1.2 in 2 categories; 3 gaps are clear of the uncertainty.
  • The widest gap is in math, where Muse Spark 1.2 leads 43.8 to 29.3.
  • The biggest single-benchmark swing is ProofBench: 9% for GPT-5.1-Codex and 43% for Muse Spark 1.2.
  • Muse Spark 1.2 is cheaper at $1.25 / $4.25 per million input/output tokens, against $1.25 / $10 for GPT-5.1-Codex.
  • Muse Spark 1.2 accepts more context: 1.05M tokens versus 400K.

Side by side

GPT-5.1-CodexMuse Spark 1.2
ProviderOpenAIMeta
Noometry Index38.249.8
Released2025-11-122026-08-05
WeightsProprietaryProprietary
Context window400K1.05M
Max output128K131K
Input $ / M tokens$1.25$1.25
Output $ / M tokens$10$4.25
Results tracked628

Sponsored placements are available on pages like this one. Advertise on Noometry

Category by category

Coding Muse Spark 1.2 leads

GPT-5.1-Codex: 41.7 (#107), Muse Spark 1.2: 48.6 (#49)

BenchmarkGPT-5.1-CodexMuse Spark 1.2
LMArena WebDev13371532
DeepSWE—54.9%
SWE-bench Verified (bash only)66%—
FrontierSWE—12%
SciCode—56.4%
WeirdML—60.3%
LMArena Coding—1497
ALE-Bench1,245—

Agentic & Tool Use GPT-5.1-Codex leads

GPT-5.1-Codex: 37.8 (#32), Muse Spark 1.2: 29.5 (#77)

BenchmarkGPT-5.1-CodexMuse Spark 1.2
Terminal-Bench60.4%—
APEX-Agents—36.4%
GDP.pdf—16%
METR Time Horizons70.8%—

Reasoning Not comparable

GPT-5.1-Codex: —, Muse Spark 1.2: 50.4 (#32)

BenchmarkGPT-5.1-CodexMuse Spark 1.2
SimpleBench—74.5%
NYT Connections (extended)—79.2%
CritPt—17.7%
LMArena Hard Prompts—1490
DTBench—94.7%
LMCA—48.4%
Epoch Capabilities Index—155.18

Math Muse Spark 1.2 leads

GPT-5.1-Codex: 29.3 (#218), Muse Spark 1.2: 43.8 (#68)

BenchmarkGPT-5.1-CodexMuse Spark 1.2
ProofBench9%43%

Knowledge Not comparable

GPT-5.1-Codex: —, Muse Spark 1.2: 53.9 (#49)

BenchmarkGPT-5.1-CodexMuse Spark 1.2
SimpleQA Verified—60.3%
LMArena Expert—1485

Multimodal Not comparable

GPT-5.1-Codex: —, Muse Spark 1.2: 42.6 (#24)

BenchmarkGPT-5.1-CodexMuse Spark 1.2
LMArena Vision—1304

Multilingual Not comparable

GPT-5.1-Codex: —, Muse Spark 1.2: 57.4 (#10)

BenchmarkGPT-5.1-CodexMuse Spark 1.2
LMArena Non-English—1479
LMArena Chinese—1519
LMArena Russian—1494

Instruction Following Not comparable

GPT-5.1-Codex: —, Muse Spark 1.2: 77.1 (#30)

BenchmarkGPT-5.1-CodexMuse Spark 1.2
LMArena Instruction Following—1466

Long Context Not comparable

GPT-5.1-Codex: —, Muse Spark 1.2: 45.4 (#35)

BenchmarkGPT-5.1-CodexMuse Spark 1.2
LMArena Longer Query—1483

Writing & Preference Not comparable

GPT-5.1-Codex: —, Muse Spark 1.2: 72.6 (#14)

BenchmarkGPT-5.1-CodexMuse Spark 1.2
LMArena Text—1486
LMArena Creative Writing—1444
EQ-Bench Creative Writing—1840
LMArena Multi-Turn—1504

Frequently asked questions

Is GPT-5.1-Codex better than Muse Spark 1.2?

Muse Spark 1.2 is the stronger model overall, scoring 49.8 to 38.2 on the Noometry Index.

Which is cheaper, GPT-5.1-Codex or Muse Spark 1.2?

Muse Spark 1.2 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 1.2 better for coding?

Muse Spark 1.2 scores higher on coding benchmarks: 48.6 versus 41.7 in the Noometry coding category.

Which has the bigger context window?

Muse Spark 1.2 does, with 1.05M tokens against 400K.

How many benchmarks do GPT-5.1-Codex and Muse Spark 1.2 share?

2 benchmarks have published results for both models. GPT-5.1-Codex has 6 scored results on Noometry and Muse Spark 1.2 has 28.

Related comparisons

Go deeper