GLM 5.3 Flash vs GPT-5.2-Codex
GLM 5.3 Flash 
GPT-5.2-Codex Verdict
- GLM 5.3 Flash and GPT-5.2-Codex are level on quality (61.1 vs 60.8).
- GLM 5.3 Flash is stronger in coding, composite, human preference, knowledge, multimodal, reasoning.
- GPT-5.2-Codex is stronger in agents & tools, long context, instruction following.
- GLM 5.3 Flash is 40× cheaper ($0.119 vs $4.81 per 1M blended).
- GLM 5.3 Flash streams 3.6× faster (90 vs 25 tokens per second).
| Metric | GLM 5.3 Flash | GPT-5.2-Codex |
|---|---|---|
| BenchLeader Index | 61.1 | 60.8 |
| Agents & tools score | 52.1 | 63.5 |
| Coding score | 64.3 | 55.7 |
| Composite score | 61.7 | 56.8 |
| Human preference score | 67.6 | – |
| Knowledge score | 67.7 | 63.1 |
| Long context score | 66.6 | 67.8 |
| Multimodal score | 65.5 | 60.7 |
| Reasoning score | 67.5 | – |
| Instruction following score | – | 75.1 |
| Blended price $/M | $0.119 | $4.81 |
| Output speed | 90 tok/s | 25 tok/s |
| Time to first answer | 24.9 s | 6.7 s |
| Context window | 1M | 400k |
| Terminal-Bench | – | 66.5% |
| SciCode | 46.1% | – |
| APEX-Agents | – | 27.6% |
| Epoch Capabilities Index | 151.4 | – |
| LMArena Text | 1474 | – |
| LMArena Hard Prompts | 1496 | – |
| LMArena Coding | 1534 | – |
| LMArena WebDev | 1605 | 1339 |
| LMArena Vision | 1296 | – |
| LMArena Agent | 2 | – |
| LiveBench | 71.6% | 74.0% |
| LiveBench Reasoning | 77.6% | 77.7% |
| LiveBench Coding | 79.0% | 83.6% |
| LiveBench Agentic Coding | 56.8% | 49.4% |
| LiveBench Mathematics | 81.2% | 88.8% |
| LiveBench Data Analysis | 76.4% | 78.2% |
| LiveBench Language | 77.3% | 73.7% |
| AA Intelligence Index | 41.9 | 28.5 |
| IFBench | – | 77.6% |
| AA-LCR | 80.0% | 82.3% |
| MMMU-Pro | – | 76.3% |
| AA-Omniscience | 7.5 | -2.2 |
| Terminal-Bench Hard | – | 37.1% |
| GPQA Diamond (AA) | 91.2% | 89.9% |
| Humanity's Last Exam (AA) | 39.9% | 35.7% |
| SciCode (AA) | 51.6% | – |
| τ²-Bench Telecom (AA) | – | 92.1% |
| LiveCodeBench | – | 88.0% |
| SWE-Bench Pro | – | 41.0% |
| SWE-bench Verified (bash only) | – | 72.8% |
| SWE-bench Verified (any scaffold) | – | 72.8% |
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-5.2-Codex: questions
- Is GLM 5.3 Flash better than GPT-5.2-Codex?
- GLM 5.3 Flash and GPT-5.2-Codex are level on quality (61.1 vs 60.8). The BenchLeader Index combines every independent quality benchmark; GLM 5.3 Flash is ahead overall as of 2026-09-10, but check the category scores for your use.
- Is GLM 5.3 Flash better than GPT-5.2-Codex for coding?
- GLM 5.3 Flash scores higher in coding (64 vs 56 on the category index, where 50 is average).
- Is GLM 5.3 Flash better than GPT-5.2-Codex for agentic tasks?
- GPT-5.2-Codex scores higher in agentic tasks (64 vs 52 on the category index, where 50 is average).
- Which is cheaper, GLM 5.3 Flash or GPT-5.2-Codex?
- GLM 5.3 Flash is cheaper: $0.119 against $4.81 per million tokens, blended at three input tokens per output token.
- Which is faster, GLM 5.3 Flash or GPT-5.2-Codex?
- GLM 5.3 Flash streams faster: 90 against 25 output tokens per second.
- Which has the larger context window?
- GLM 5.3 Flash accepts more context: 1M against 400k tokens.