GLM 5.3 Flash vs GPT-5.5
GLM 5.3 Flash 
GPT-5.5 Verdict
- GPT-5.5 leads on quality: 66.7 vs 61.1.
- GLM 5.3 Flash is stronger in coding, multimodal.
- GPT-5.5 is stronger in agents & tools, composite, human preference, knowledge, long context, reasoning, instruction following.
- GLM 5.3 Flash is 95× cheaper ($0.119 vs $11.25 per 1M blended).
| Metric | GLM 5.3 Flash | GPT-5.5 |
|---|---|---|
| BenchLeader Index | 61.1 | 66.7 |
| Agents & tools score | 52.1 | 68.5 |
| Coding score | 64.3 | 57.2 |
| Composite score | 61.7 | 77.8 |
| Human preference score | 67.6 | 67.9 |
| Knowledge score | 67.7 | 73.9 |
| Long context score | 66.6 | 68.8 |
| Multimodal score | 65.5 | 64.9 |
| Reasoning score | 67.5 | 70.1 |
| Instruction following score | – | 73.6 |
| Blended price $/M | $0.119 | $11.25 |
| Output speed | 90 tok/s | 85 tok/s |
| Time to first answer | 24.9 s | 58.6 s |
| Context window | 1M | 1.1M |
| Terminal-Bench | – | 84.7% |
| SimpleBench | – | 69.0% |
| SciCode | 46.1% | – |
| Remote Labor Index | – | 6.3% |
| APEX-Agents | – | 38.5% |
| FrontierCode | – | 43.0% |
| Epoch Capabilities Index | 151.4 | 159.1 |
| LMArena Text | 1474 | 1477 |
| LMArena Hard Prompts | 1496 | 1498 |
| LMArena Coding | 1534 | 1509 |
| LMArena WebDev | 1605 | 1458 |
| LMArena Vision | 1296 | 1296 |
| LMArena Agent | 2 | 3 |
| LiveBench | 71.6% | – |
| LiveBench Reasoning | 77.6% | – |
| LiveBench Coding | 79.0% | – |
| LiveBench Agentic Coding | 56.8% | – |
| LiveBench Mathematics | 81.2% | – |
| LiveBench Data Analysis | 76.4% | – |
| LiveBench Language | 77.3% | – |
| AA Intelligence Index | 41.9 | 38.6 |
| IFBench | – | 75.8% |
| AA-LCR | 80.0% | 84.3% |
| MMMU-Pro | – | 79.9% |
| AA-Omniscience | 7.5 | 20.5 |
| Terminal-Bench Hard | – | 60.6% |
| GPQA Diamond (AA) | 91.2% | 93.5% |
| Humanity's Last Exam (AA) | 39.9% | 45.8% |
| SciCode (AA) | 51.6% | 55.8% |
| τ²-Bench Telecom (AA) | – | 93.9% |
| 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 5.3 Flash vs GPT-5.5: questions
- Is GLM 5.3 Flash better than GPT-5.5?
- GPT-5.5 leads on quality: 66.7 vs 61.1. 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 5.3 Flash better than GPT-5.5 for coding?
- GLM 5.3 Flash scores higher in coding (64 vs 57 on the category index, where 50 is average).
- Is GLM 5.3 Flash better than GPT-5.5 for agentic tasks?
- GPT-5.5 scores higher in agentic tasks (69 vs 52 on the category index, where 50 is average).
- Which is cheaper, GLM 5.3 Flash or GPT-5.5?
- GLM 5.3 Flash is cheaper: $0.119 against $11.25 per million tokens, blended at three input tokens per output token.
- Which is faster, GLM 5.3 Flash or GPT-5.5?
- GLM 5.3 Flash streams faster: 90 against 85 output tokens per second.
- Which has the larger context window?
- GPT-5.5 accepts more context: 1.1M against 1M tokens.