GPT-5.3-Codex vs Muse Spark 1.2
GPT-5.3-Codex 
Muse Spark 1.2 Verdict
- GPT-5.3-Codex and Muse Spark 1.2 are level on quality (62.5 vs 62.7).
- GPT-5.3-Codex is stronger in agents & tools, instruction following, long context, multimodal.
- Muse Spark 1.2 is stronger in coding, composite, knowledge, maths, reasoning.
- Muse Spark 1.2 is 2.4× cheaper ($2.00 vs $4.81 per 1M blended).
- Muse Spark 1.2 streams 1.6× faster (193 vs 121 tokens per second).
| Metric | GPT-5.3-Codex | Muse Spark 1.2 |
|---|---|---|
| BenchLeader Index | 62.5 | 62.7 |
| Agents & tools score | 62.7 | – |
| Coding score | 54.8 | 66.5 |
| Composite score | 70.1 | 79.3 |
| Instruction following score | 73.2 | – |
| Knowledge score | 69.3 | 77.1 |
| Long context score | 68.3 | 66.0 |
| Multimodal score | 63.0 | – |
| Maths score | – | 54.3 |
| Reasoning score | – | 70.7 |
| Blended price $/M | $4.81 | $2.00 |
| Output speed | 121 tok/s | 193 tok/s |
| Time to first answer | 58.2 s | 23.4 s |
| Context window | 400k | 1.0M |
| Terminal-Bench | 78.4% | – |
| SimpleBench | – | 74.5% |
| WeirdML | 79.3% | – |
| APEX-Agents | 31.8% | – |
| ProofBench | – | 43.0% |
| Epoch Capabilities Index | 156.6 | 155.5 |
| LMArena WebDev | 1409 | – |
| AA Intelligence Index | 32.5 | 39.8 |
| IFBench | 75.4% | – |
| AA-LCR | 83.3% | 79.0% |
| MMMU-Pro | 78.5% | – |
| AA-Omniscience | 10.9 | 27.2 |
| Terminal-Bench Hard | 53.0% | – |
| GPQA Diamond (AA) | 91.5% | 90.4% |
| Humanity's Last Exam (AA) | 42.5% | 45.5% |
| SciCode (AA) | – | 57.4% |
| τ²-Bench Telecom (AA) | 86.0% | – |
| IOI | – | 49.5% |
| HiL-Bench | 4.3% | – |
Data as of 2026-09-10. Best configuration of each model; every score links to its source on the model pages.
GPT-5.3-Codex vs Muse Spark 1.2: questions
- Is GPT-5.3-Codex better than Muse Spark 1.2?
- GPT-5.3-Codex and Muse Spark 1.2 are level on quality (62.5 vs 62.7). The BenchLeader Index combines every independent quality benchmark; Muse Spark 1.2 is ahead overall as of 2026-09-10, but check the category scores for your use.
- Is GPT-5.3-Codex better than Muse Spark 1.2 for coding?
- Muse Spark 1.2 scores higher in coding (67 vs 55 on the category index, where 50 is average).
- Which is cheaper, GPT-5.3-Codex or Muse Spark 1.2?
- Muse Spark 1.2 is cheaper: $2.00 against $4.81 per million tokens, blended at three input tokens per output token.
- Which is faster, GPT-5.3-Codex or Muse Spark 1.2?
- Muse Spark 1.2 streams faster: 193 against 121 output tokens per second.
- Which has the larger context window?
- Muse Spark 1.2 accepts more context: 1.0M against 400k tokens.