GLM 5.1 vs GPT-5.5
GLM 5.1 
GPT-5.5 Verdict
- GPT-5.5 leads on quality: 66.7 vs 60.2.
- GLM 5.1 is stronger in coding, instruction following, maths.
- GPT-5.5 is stronger in agents & tools, composite, human preference, knowledge, long context, reasoning, multimodal.
- GLM 5.1 is 5.2× cheaper ($2.15 vs $11.25 per 1M blended).
- GPT-5.5 streams 1.3× faster (85 vs 65 tokens per second).
| Metric | GLM 5.1 | GPT-5.5 |
|---|---|---|
| BenchLeader Index | 60.2 | 66.7 |
| Agents & tools score | 56.8 | 68.5 |
| Coding score | 57.3 | 57.2 |
| Composite score | 62.4 | 77.8 |
| Human preference score | 66.6 | 67.9 |
| Instruction following score | 73.9 | 73.6 |
| Knowledge score | 56.6 | 73.9 |
| Long context score | 63.3 | 68.8 |
| Maths score | 53.0 | – |
| Reasoning score | 61.4 | 70.1 |
| Multimodal score | – | 64.9 |
| Blended price $/M | $2.15 | $11.25 |
| Output speed | 65 tok/s | 85 tok/s |
| Time to first answer | 60.1 s | 58.6 s |
| Context window | 200k | 1.1M |
| GPQA Diamond | 89.9% | – |
| FrontierMath Tiers 1–3 | 36.8% | – |
| OTIS Mock AIME | 93.3% | – |
| SWE-bench Verified (Epoch) | 74.2% | – |
| SimpleQA Verified | 34.0% | – |
| Terminal-Bench | – | 84.7% |
| SimpleBench | 55.1% | 69.0% |
| SciCode | 43.8% | – |
| Remote Labor Index | – | 6.3% |
| WeirdML | 57.1% | – |
| APEX-Agents | – | 38.5% |
| FrontierCode | – | 43.0% |
| ProofBench | 22.2% | – |
| Epoch Capabilities Index | 149.7 | 159.1 |
| LMArena Text | 1466 | 1477 |
| LMArena Hard Prompts | 1489 | 1498 |
| LMArena Coding | 1514 | 1509 |
| LMArena WebDev | 1508 | 1458 |
| LMArena Vision | – | 1296 |
| LMArena Agent | – | 3 |
| AA Intelligence Index | 26.4 | 38.6 |
| IFBench | 76.3% | 75.8% |
| AA-LCR | 73.7% | 84.3% |
| MMMU-Pro | – | 79.9% |
| AA-Omniscience | 0.8 | 20.5 |
| Terminal-Bench Hard | 43.2% | 60.6% |
| GPQA Diamond (AA) | 86.8% | 93.5% |
| Humanity's Last Exam (AA) | 30.1% | 45.8% |
| SciCode (AA) | 44.8% | 55.8% |
| τ²-Bench Telecom (AA) | 97.7% | 93.9% |
| AIME (Vals) | 91.9% | – |
| LiveCodeBench | 81.4% | – |
| MMLU-Pro | 86.9% | – |
| LegalBench | 84.4% | – |
| CorpFin | 64.5% | – |
| TaxEval | 71.2% | – |
| Terminal-Bench 2.1 (Vals) | 56.9% | – |
| SWE-bench (Vals) | 76.4% | – |
| GPQA Diamond (Vals) | 84.5% | – |
| AIME 2026 | 95.8% | – |
| HMMT February 2026 | 89.4% | – |
| MathArena Apex | 11.5% | – |
| MCP Atlas | 75.6% | – |
| HiL-Bench | – | 39.7% |
| EQ-Bench 4 | – | 1315 |
| Kagi LLM Benchmark | – | 88.8% |
Data as of 2026-09-10. Best configuration of each model; every score links to its source on the model pages.
GLM 5.1 vs GPT-5.5: questions
- Is GLM 5.1 better than GPT-5.5?
- GPT-5.5 leads on quality: 66.7 vs 60.2. The BenchLeader Index combines every independent quality benchmark; GPT-5.5 is ahead overall as of 2026-09-10, but check the category scores for your use.
- Is GLM 5.1 better than GPT-5.5 for coding?
- GLM 5.1 scores higher in coding (57 vs 57 on the category index, where 50 is average).
- Is GLM 5.1 better than GPT-5.5 for agentic tasks?
- GPT-5.5 scores higher in agentic tasks (69 vs 57 on the category index, where 50 is average).
- Which is cheaper, GLM 5.1 or GPT-5.5?
- GLM 5.1 is cheaper: $2.15 against $11.25 per million tokens, blended at three input tokens per output token.
- Which is faster, GLM 5.1 or GPT-5.5?
- GPT-5.5 streams faster: 85 against 65 output tokens per second.
- Which has the larger context window?
- GPT-5.5 accepts more context: 1.1M against 200k tokens.