Noometry

Model comparison

GPT-5.3 Codex vs Muse Spark 1.2

Muse Spark 1.2 is the stronger model overall, scoring 49.8 to 45.5 on the Noometry Index.

Last verified . 3 shared benchmarks.

GPT-5.3 Codex OpenAI

45.5

Rank #61 Reported

Muse Spark 1.2 Meta

49.8

Rank #44 Confirmed

Summary

  • They share 3 benchmarks with published results for both. GPT-5.3 Codex scores higher in 1 category and Muse Spark 1.2 in 1 category; one gap is clear of the uncertainty.
  • The widest gap is in agentic & tool use, where GPT-5.3 Codex leads 47.8 to 29.5.
  • The biggest single-benchmark swing is WeirdML: 79.3% for GPT-5.3 Codex and 60.3% for Muse Spark 1.2.
  • Muse Spark 1.2 is cheaper at $1.25 / $4.25 per million input/output tokens, against $1.75 / $14 for GPT-5.3 Codex.
  • Muse Spark 1.2 accepts more context: 1.05M tokens versus 400K.

Side by side

GPT-5.3 CodexMuse Spark 1.2
ProviderOpenAIMeta
Noometry Index45.549.8
Released2026-02-052026-08-05
WeightsProprietaryProprietary
Context window400K1.05M
Max output128K131K
Input $ / M tokens$1.75$1.25
Output $ / M tokens$14$4.25
Results tracked828

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Category by category

Coding Too close to call

GPT-5.3 Codex: 48.5 (#51), Muse Spark 1.2: 48.6 (#49)

BenchmarkGPT-5.3 CodexMuse Spark 1.2
LMArena WebDev14081532
WeirdML79.3%60.3%
SWE-bench Verified74.8%—
DeepSWE—54.9%
FrontierSWE—12%
SciCode—56.4%
LMArena Coding—1497
ALE-Bench1,655—

Agentic & Tool Use GPT-5.3 Codex leads

GPT-5.3 Codex: 47.8 (#9), Muse Spark 1.2: 29.5 (#77)

BenchmarkGPT-5.3 CodexMuse Spark 1.2
Terminal-Bench78.4%—
APEX-Agents—36.4%
GDP.pdf—16%
METR Time Horizons74.5%—
Vending-Bench 25,940—

Reasoning Not comparable

GPT-5.3 Codex: —, Muse Spark 1.2: 50.4 (#32)

BenchmarkGPT-5.3 CodexMuse Spark 1.2
Epoch Capabilities Index156.84155.18
SimpleBench—74.5%
NYT Connections (extended)—79.2%
CritPt—17.7%
LMArena Hard Prompts—1490
DTBench—94.7%
LMCA—48.4%

Math Not comparable

GPT-5.3 Codex: —, Muse Spark 1.2: 43.8 (#68)

BenchmarkGPT-5.3 CodexMuse Spark 1.2
ProofBench—43%

Knowledge Not comparable

GPT-5.3 Codex: —, Muse Spark 1.2: 53.9 (#49)

BenchmarkGPT-5.3 CodexMuse Spark 1.2
SimpleQA Verified—60.3%
LMArena Expert—1485

Multimodal Not comparable

GPT-5.3 Codex: —, Muse Spark 1.2: 42.6 (#24)

BenchmarkGPT-5.3 CodexMuse Spark 1.2
LMArena Vision—1304

Multilingual Not comparable

GPT-5.3 Codex: —, Muse Spark 1.2: 57.4 (#10)

BenchmarkGPT-5.3 CodexMuse Spark 1.2
LMArena Non-English—1479
LMArena Chinese—1519
LMArena Russian—1494

Instruction Following Not comparable

GPT-5.3 Codex: —, Muse Spark 1.2: 77.1 (#30)

BenchmarkGPT-5.3 CodexMuse Spark 1.2
LMArena Instruction Following—1466

Long Context Not comparable

GPT-5.3 Codex: —, Muse Spark 1.2: 45.4 (#35)

BenchmarkGPT-5.3 CodexMuse Spark 1.2
LMArena Longer Query—1483

Writing & Preference Not comparable

GPT-5.3 Codex: —, Muse Spark 1.2: 72.6 (#14)

BenchmarkGPT-5.3 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-5.3 Codex better than Muse Spark 1.2?

Muse Spark 1.2 is the stronger model overall, scoring 49.8 to 45.5 on the Noometry Index.

Which is cheaper, GPT-5.3 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-5.3 Codex lists at $1.75 and $14.

Is GPT-5.3 Codex or Muse Spark 1.2 better for coding?

They score almost the same on coding (48.5 vs 48.6); test both on your own repository before choosing.

Which has the bigger context window?

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

How many benchmarks do GPT-5.3 Codex and Muse Spark 1.2 share?

3 benchmarks have published results for both models. GPT-5.3 Codex has 8 scored results on Noometry and Muse Spark 1.2 has 28.

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