GLM-5.3 vs GPT-5.5 Pro
GLM-5.3 
GPT-5.5 Pro Verdict
- GPT-5.5 Pro (xhigh) leads on quality: 67.1 vs 65.8.
- GLM-5.3 (max) is stronger in agents & tools, coding, composite, human preference, knowledge, long context.
- GPT-5.5 Pro (xhigh) is stronger in maths, reasoning.
- GLM-5.3 (max) is 31× cheaper ($2.15 vs $67.50 per 1M blended).
- GLM-5.3 (max) streams 15.8× faster (63 vs 4 tokens per second).
| Metric | GLM-5.3 (max) | GPT-5.5 Pro (xhigh) |
|---|---|---|
| BenchLeader Index | 65.8 | 67.1 |
| Agents & tools score | 62.0 | – |
| Coding score | 64.4 | – |
| Composite score | 85.9 | – |
| Human preference score | 68.5 | – |
| Knowledge score | 59.6 | – |
| Long context score | 66.3 | – |
| Maths score | 62.7 | 74.5 |
| Reasoning score | 71.6 | 80.1 |
| Blended price $/M | $2.15 | $67.50 |
| Output speed | 63 tok/s | 4 tok/s |
| Time to first answer | 34.6 s | 3.5 s |
| Context window | 1M | 1.1M |
| GPQA Diamond | 90.9% | – |
| FrontierMath Tiers 1–3 | 68.8% | 87.7% |
| FrontierMath Tier 4 | 29.3% | 78.0% |
| OTIS Mock AIME | 91.1% | – |
| SimpleQA Verified | 41.0% | – |
| Terminal-Bench | 41.8% | – |
| SciCode | 56.5% | – |
| WeirdML | 75.4% | – |
| ProofBench | 49.0% | – |
| LMArena Text | 1483 | – |
| LMArena Hard Prompts | 1507 | – |
| LMArena Coding | 1524 | – |
| LMArena WebDev | 1614 | – |
| LMArena Agent | 3.1 | – |
| AA Intelligence Index | 44.9 | – |
| AA-LCR | 79.7% | – |
| AA-Omniscience | 14.3 | – |
| GPQA Diamond (AA) | 91.7% | – |
| Humanity's Last Exam (AA) | 42.3% | – |
| SciCode (AA) | 59.0% | – |
| LiveCodeBench | 80.5% | – |
| MMLU-Pro | 86.8% | – |
| IOI | 68.4% | – |
| LegalBench | 84.8% | – |
| TaxEval | 72.4% | – |
| Terminal-Bench 2.1 (Vals) | 71.5% | – |
| SWE-bench (Vals) | 95.4% | – |
| GPQA Diamond (Vals) | 88.1% | – |
| Vals Index | 57.0 | – |
| ARC-AGI-1 | – | 95.0% |
| ARC-AGI-2 | – | 84.2% |
| CritPt | 19.1% | 30.6% |
| GDPval (AA) | 56.7% | – |
| τ²-Bench Banking (AA) | 50.3% | – |
| Code Migration | 44.2% | – |
| Excel Modeling Benchmark | 56.3% | – |
| Finance Agent v2 | 55.8% | – |
| Harvey's Legal Agent Benchmark | 8.3% | – |
| Legal Research Bench | 49.0% | – |
| MedCode | 42.9% | – |
| MedScribe | 88.8% | – |
| MysteryMechanism | 23.0% | – |
| ProgramBench | 1.5% | – |
| Public Benefits Bench | 68.5% | – |
| SkillsBench | 47.5% | – |
| Tax Agent Bench | 73.1% | – |
| Terminal-Bench 4.0 (Vals) | 25.3% | – |
| Terminal-Bench Science | 4.3% | – |
| Vibe Code Bench 1-100 | 20.0% | – |
| Vibe Code Bench v1.1 | 78.1% | – |
| FORTRESS | 28.2% | – |
| LMArena Maths | 1504 | – |
| LMArena Creative Writing | 1462 | – |
| LMArena Instruction Following | 1480 | – |
| LMArena Multi-turn | 1493 | – |
| LMArena Longer Queries | 1492 | – |
| Chess Puzzles | 21.0% | – |
| Mystery Game Puzzles | 33.0% | – |
| DeepSWE | 69.0% | – |
| LMCA | – | 53.9% |
| DTBench | – | 96.0% |
| FrontierSWE | 30.2% | – |
Data as of 2026-09-19. Best configuration of each model; every score links to its source on the model pages.
GLM-5.3 vs GPT-5.5 Pro: questions
- Is GLM-5.3 better than GPT-5.5 Pro?
- GPT-5.5 Pro (xhigh) leads on quality: 67.1 vs 65.8. The BenchLeader Index combines every independent quality benchmark; GPT-5.5 Pro (xhigh) is ahead overall as of 2026-09-19, but check the category scores for your use.
- Which is cheaper, GLM-5.3 or GPT-5.5 Pro?
- GLM-5.3 is cheaper: $2.15 against $67.50 per million tokens, blended at three input tokens per output token.
- Which is faster, GLM-5.3 or GPT-5.5 Pro?
- GLM-5.3 streams faster: 63 against 4 output tokens per second.
- Which has the larger context window?
- GPT-5.5 Pro accepts more context: 1.1M against 1M tokens.