Model comparison
GPT-5.1-Codex vs Muse Spark 1.3
Muse Spark 1.3 is the stronger model overall, scoring 54.8 to 38.6 on the Noometry Index.
Last verified . 2 shared benchmarks.
MetaSummary
- They share 2 benchmarks with published results for both. GPT-5.1-Codex scores higher in 0 categories and Muse Spark 1.3 in 3 categories; 2 gaps are clear of the uncertainty.
- The widest gap is in math, where Muse Spark 1.3 leads 73.1 to 30.3.
- The biggest single-benchmark swing is ProofBench: 9% for GPT-5.1-Codex and 58% for Muse Spark 1.3.
- Muse Spark 1.3 is cheaper at $1.25 / $4.25 per million input/output tokens, against $1.25 / $10 for GPT-5.1-Codex.
- Muse Spark 1.3 accepts more context: 1.05M tokens versus 400K.
Side by side
| GPT-5.1-Codex | Muse Spark 1.3 | |
|---|---|---|
| Provider | OpenAI | Meta |
| Noometry Index | 38.6 | 54.8 |
| Released | 2025-11-12 | 2026-09-02 |
| Weights | Proprietary | Proprietary |
| Context window | 400K | 1.05M |
| Max output | 128K | 131K |
| Input $ / M tokens | $1.25 | $1.25 |
| Output $ / M tokens | $10 | $4.25 |
| Results tracked | 6 | 37 |
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Category by category
Coding Muse Spark 1.3 leads
GPT-5.1-Codex: 41.9 (#116), Muse Spark 1.3: 56.6 (#21)
| Benchmark | GPT-5.1-Codex | Muse Spark 1.3 |
|---|---|---|
| LMArena WebDev | 1337 | 1657 |
| SWE-bench Verified (bash only) | 66% | — |
| CursorBench | — | 41.6% |
| SciCode | — | 59.7% |
| LMArena Coding | — | 1514 |
| ALE-Bench | 1,245 | — |
Agentic & Tool Use Too close to call
GPT-5.1-Codex: 38.0 (#33), Muse Spark 1.3: 38.6 (#30)
| Benchmark | GPT-5.1-Codex | Muse Spark 1.3 |
|---|---|---|
| Terminal-Bench | 60.4% | — |
| APEX-Agents | — | 57.8% |
| GDP.pdf | — | 27.6% |
| METR Time Horizons | 70.8% | — |
Reasoning Not comparable
GPT-5.1-Codex: —, Muse Spark 1.3: 54.0 (#27)
| Benchmark | GPT-5.1-Codex | Muse Spark 1.3 |
|---|---|---|
| NYT Connections (extended) | — | 85.1% |
| CritPt | — | 26% |
| Chess Puzzles | — | 38% |
| LMArena Hard Prompts | — | 1503 |
| Mystery Game Puzzles | — | 25% |
| DTBench | — | 96.5% |
| LMCA | — | 53.9% |
| Bench to the Future 3 | — | 0.14 |
| Epoch Capabilities Index | — | 156.75 |
Math Muse Spark 1.3 leads
GPT-5.1-Codex: 30.3 (#235), Muse Spark 1.3: 73.1 (#21)
| Benchmark | GPT-5.1-Codex | Muse Spark 1.3 |
|---|---|---|
| ProofBench | 9% | 58% |
| FrontierMath (Tiers 1-3) | — | 74.4% |
| FrontierMath Tier 4 | — | 46.3% |
| OTIS Mock AIME 2024-2025 | — | 99.2% |
| LMArena Math | — | 1494 |
Knowledge Not comparable
GPT-5.1-Codex: —, Muse Spark 1.3: 42.6 (#95)
| Benchmark | GPT-5.1-Codex | Muse Spark 1.3 |
|---|---|---|
| LMArena Expert | — | 1516 |
Multimodal Not comparable
GPT-5.1-Codex: —, Muse Spark 1.3: 43.7 (#22)
| Benchmark | GPT-5.1-Codex | Muse Spark 1.3 |
|---|---|---|
| LMArena Vision | — | 1309 |
| LMArena Document | — | 1471 |
Multilingual Not comparable
GPT-5.1-Codex: —, Muse Spark 1.3: 57.4 (#8)
| Benchmark | GPT-5.1-Codex | Muse Spark 1.3 |
|---|---|---|
| LMArena Non-English | — | 1481 |
| LMArena Chinese | — | 1529 |
| LMArena French | — | 1524 |
| LMArena German | — | 1515 |
| LMArena Japanese | — | 1474 |
| LMArena Korean | — | 1501 |
| LMArena Russian | — | 1490 |
| LMArena Spanish | — | 1490 |
Instruction Following Not comparable
GPT-5.1-Codex: —, Muse Spark 1.3: 77.5 (#22)
| Benchmark | GPT-5.1-Codex | Muse Spark 1.3 |
|---|---|---|
| LMArena Instruction Following | — | 1477 |
Long Context Not comparable
GPT-5.1-Codex: —, Muse Spark 1.3: 45.6 (#32)
| Benchmark | GPT-5.1-Codex | Muse Spark 1.3 |
|---|---|---|
| LMArena Longer Query | — | 1488 |
Writing & Preference Not comparable
GPT-5.1-Codex: —, Muse Spark 1.3: 73.6 (#9)
| Benchmark | GPT-5.1-Codex | Muse Spark 1.3 |
|---|---|---|
| LMArena Text | — | 1490 |
| LMArena Creative Writing | — | 1455 |
| EQ-Bench Creative Writing | — | 1906 |
| LMArena Multi-Turn | — | 1482 |
Frequently asked questions
Is GPT-5.1-Codex better than Muse Spark 1.3?
Muse Spark 1.3 is the stronger model overall, scoring 54.8 to 38.6 on the Noometry Index.
Which is cheaper, GPT-5.1-Codex or Muse Spark 1.3?
Muse Spark 1.3 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 1.3 better for coding?
Muse Spark 1.3 scores higher on coding benchmarks: 56.6 versus 41.9 in the Noometry coding category.
Which has the bigger context window?
Muse Spark 1.3 does, with 1.05M tokens against 400K.
How many benchmarks do GPT-5.1-Codex and Muse Spark 1.3 share?
2 benchmarks have published results for both models. GPT-5.1-Codex has 6 scored results on Noometry and Muse Spark 1.3 has 37.